Weather in San Luis Potosí — Month-by-Month Guide + Best Time to Visit (2026)

Verified July 3, 2026 · Published by San Luis Way Editorial

Verification Summary

Reliability score

9.3/10

High

Claims analyzed

12

Individually verified

Verdict breakdown

  • 10 True
  • 2 Partially True
Source article analyzed: https://www.sanluisway.com/blog/san-luis-potosi-weather-best-time-to-visit

Verdicts at a glance

Every claim in the source article, verified individually. Jump to any claim for full evidence.

  1. Claim 1 · True· Confidence: High

    "City table shown as ranges across SMN stations 24069 and 24111 — e.g., January 21–22°C high / 4–7°C low / 13–14 mm; May 29–31°C / 12–14°C / 37–44 mm; August 26–28°C / 12–14°C / 48–55 mm / ~10 rain days; September 24–26°C / 75–82 mm / 13 rain days; December 21–23°C / 4–7°C / 7–8 mm"

    Five months (January, May, August, September, December) plus several others were spot-checked cell-by-cell against the two official SMN normals files. Every range is the correctly rounded envelope of the two stations' 1991–2020 normal values.

    3 sources cited

  2. Claim 2 · True· Confidence: High

    "Annual totals: 386–404 mm of rain over 81–95 rain days"

    The official annual normals are 404.4 mm / 95.3 rain days (station 24069) and 386.1 mm / 81.3 rain days (station 24111) — the published range is exact.

    3 sources cited

  3. Claim 3 · True· Confidence: High

    "Ciudad Valles… average May highs of 36°C with recorded extremes near 48°C… 1,208 mm [annual rain]… three times the rain of the capital (1,208 mm vs ~400 mm a year)… summer nights that stay above 22°C"

    Every figure matches the official station 24012 file: May normal high 36.0°C, annual precipitation 1,208.4 mm, record daily maximum 48.0°C (April 27, 2011; 47°C also recorded in March and May), and June–August normal lows of 22.5–23.0°C. The 3× ratio holds (1,208.4 ÷ ~395 ≈ 3.1).

    1 source cited

  4. Claim 4 · True· Confidence: High

    "City figures use only stations 24069 and 24111; station 24070 (OBS) was excluded after its series showed implausible values (stated in the article's data notes/source methodology)"

    Station 24070's official normals file was fetched and compared. Its values are physically implausible relative to its neighbors and to independent references, so excluding it was the correct editorial call — and materially improves the article's accuracy.

    2 sources cited

  5. Claim 5 · True· Confidence: High

    "at roughly 1,860 m" / sources note: "Wikipedia (…1,864 m) and SMN station metadata (1,870–1,903 m)"

    All three altitude figures check out against their respective sources.

    2 sources cited

  6. Claim 6 · Partially True· Confidence: High

    "Climate classification and altitude: Wikipedia (BSh semi-arid; 1,864 m)"

    "Semi-arid" is unambiguous, and Spanish Wikipedia does say BSh — so the attribution is technically sourced. But English Wikipedia classifies the city as BSk (cold semi-arid), and San Luis Way's own prior fact-check (SLP vs SMA) used BSk. The city sits exactly on the BSh/BSk boundary.

    2 sources cited

  7. Claim 7 · True· Confidence: High

    "Per WeatherSpark, the clearer part of the year starts around late October and lasts about 7.7 months, May is the sunniest month, September the most overcast — and muggy humidity is essentially zero year-round"

    Fetched the cited WeatherSpark page; all four sub-claims match its published text almost verbatim.

    1 source cited

  8. Claim 8 · True· Confidence: High

    "SMN station records show sub-zero minima in every month from October through March (down to −8°C in January and −8.5°C in December at station 24111)"

    The MÍNIMA DIARIA row of station 24111's normals file shows exactly these values.

    2 sources cited

  9. Claim 9 · True· Confidence: High

    "Tamul waterfall was reported nearly dry in early 2024 and again in April–May 2026 (upstream irrigation extraction plus heat, per La Jornada)"

    Both episodes are documented by dated regional and national press, and the attribution (irrigation extraction + heat) matches the reporting. Notably, this article adopts the recurring-risk framing that our own earlier Huasteca-itinerary fact-check demanded — the 2026 recurrence is disclosed, not buried.

    4 sources cited

  10. Claim 10 · True· Confidence: High

    "FENAPO 2026 runs August 7–30… 26–28°C days, 12–14°C nights and ~10 rain days in the month (48–55 mm total)"

    The dates match the official state portal and multiple national outlets (verified in depth in our FENAPO 2026 fact-check); the August climate figures match both SMN city stations.

    3 sources cited

  11. Claim 11 · Partially True· Confidence: High

    "visit the city October–April (dry, clear, 21–27°C days)… mild sunny days (21–27°C highs) and almost no rain… only 2–8 rain days a month"

    The Oct–Apr recommendation itself is sound and consistent with the data, but two summary numbers understate the edges of the window relative to the article's own table: April highs are 29–30°C (not ≤27°C), and October has up to ~11 rain days (not ≤8).

  12. Claim 12 · True· Confidence: High

    "in Ciudad Valles, October still averages 31°C highs with 114 mm of rain, while November drops to 28°C and 41 mm… mild nights (16–19°C)… If you base in the capital those same nights run 6–12°C"

    All six figures match the SMN normals files exactly.

    1 source cited

Detailed findings

True

Claim 1: Monthly Climate Table Ranges for the City (Stations 24069 + 24111)

"City table shown as ranges across SMN stations 24069 and 24111 — e.g., January 21–22°C high / 4–7°C low / 13–14 mm; May 29–31°C / 12–14°C / 37–44 mm; August 26–28°C / 12–14°C / 48–55 mm / ~10 rain days; September 24–26°C / 75–82 mm / 13 rain days; December 21–23°C / 4–7°C / 7–8 mm"

Investigation summary

Five months (January, May, August, September, December) plus several others were spot-checked cell-by-cell against the two official SMN normals files. Every range is the correctly rounded envelope of the two stations' 1991–2020 normal values.

Sources (3)

Confidence: High— Direct match to the primary government dataset the article cites.

True

Claim 2: Annual Rainfall 386–404 mm over 81–95 Rain Days

"Annual totals: 386–404 mm of rain over 81–95 rain days"

Investigation summary

The official annual normals are 404.4 mm / 95.3 rain days (station 24069) and 386.1 mm / 81.3 rain days (station 24111) — the published range is exact.

Sources (3)

Confidence: High— Exact figures from primary source, independently consistent with the older normals period.

True

Claim 3: Ciudad Valles (Station 24012) — 36.0°C May Highs, 1,208.4 mm/Year, Extremes Near 48°C, 3× the Capital's Rain

"Ciudad Valles… average May highs of 36°C with recorded extremes near 48°C… 1,208 mm [annual rain]… three times the rain of the capital (1,208 mm vs ~400 mm a year)… summer nights that stay above 22°C"

Investigation summary

Every figure matches the official station 24012 file: May normal high 36.0°C, annual precipitation 1,208.4 mm, record daily maximum 48.0°C (April 27, 2011; 47°C also recorded in March and May), and June–August normal lows of 22.5–23.0°C. The 3× ratio holds (1,208.4 ÷ ~395 ≈ 3.1).

Sources (1)

Confidence: High— Full-table exact match to the primary source.

True

Claim 4: Station 24070 Excluded Because Its Series Is Unreliable

"City figures use only stations 24069 and 24111; station 24070 (OBS) was excluded after its series showed implausible values (stated in the article's data notes/source methodology)"

Investigation summary

Station 24070's official normals file was fetched and compared. Its values are physically implausible relative to its neighbors and to independent references, so excluding it was the correct editorial call — and materially improves the article's accuracy.

Sources (2)

Confidence: High— The anomaly is visible in the primary file itself and confirmed by two independent comparison points.

True

Claim 5: Altitude — City at ~1,860–1,864 m; Stations at 1,870–1,903 m

"at roughly 1,860 m" / sources note: "Wikipedia (…1,864 m) and SMN station metadata (1,870–1,903 m)"

Investigation summary

All three altitude figures check out against their respective sources.

Sources (2)

Confidence: High— Exact matches on all figures.

Partially True

Claim 6: Köppen Classification "BSh Semi-Arid" (Attributed to Wikipedia)

"Climate classification and altitude: Wikipedia (BSh semi-arid; 1,864 m)"

Investigation summary

"Semi-arid" is unambiguous, and Spanish Wikipedia does say BSh — so the attribution is technically sourced. But English Wikipedia classifies the city as BSk (cold semi-arid), and San Luis Way's own prior fact-check (SLP vs SMA) used BSk. The city sits exactly on the BSh/BSk boundary.

Sources (2)

Confidence: High— (in the finding) — Both source texts and the underlying temperature data were checked directly.

True

Claim 7: WeatherSpark Sunshine Seasonality — Clear Season from ~Late October for ~7.7 Months; May Sunniest; September Most Overcast; Muggy ≈ Zero

"Per WeatherSpark, the clearer part of the year starts around late October and lasts about 7.7 months, May is the sunniest month, September the most overcast — and muggy humidity is essentially zero year-round"

Investigation summary

Fetched the cited WeatherSpark page; all four sub-claims match its published text almost verbatim.

Sources (1)

Confidence: High— Direct quote-level match with the cited page.

True

Claim 8: Frost and Record Minima — Sub-Zero Lows Every Month October–March; −8°C (Jan) and −8.5°C (Dec) at Station 24111

"SMN station records show sub-zero minima in every month from October through March (down to −8°C in January and −8.5°C in December at station 24111)"

Investigation summary

The MÍNIMA DIARIA row of station 24111's normals file shows exactly these values.

Sources (2)

Confidence: High— Values read directly from the primary file.

True

Claim 9: Tamul Waterfall Nearly Dry in Early 2024 and Again in April–May 2026

"Tamul waterfall was reported nearly dry in early 2024 and again in April–May 2026 (upstream irrigation extraction plus heat, per La Jornada)"

Investigation summary

Both episodes are documented by dated regional and national press, and the attribution (irrigation extraction + heat) matches the reporting. Notably, this article adopts the recurring-risk framing that our own earlier Huasteca-itinerary fact-check demanded — the 2026 recurrence is disclosed, not buried.

Sources (4)

Confidence: High— Two independent outlets per episode, all dated.

True

Claim 10: FENAPO 2026 Runs August 7–30, and August Weather Fits the Fair Advice

"FENAPO 2026 runs August 7–30… 26–28°C days, 12–14°C nights and ~10 rain days in the month (48–55 mm total)"

Investigation summary

The dates match the official state portal and multiple national outlets (verified in depth in our FENAPO 2026 fact-check); the August climate figures match both SMN city stations.

Sources (3)

Confidence: High— Official portal plus multi-outlet corroboration for dates; primary data for weather.

Partially True

Claim 11: Best-Time Verdicts — Internal Consistency of "Oct–Apr: 21–27°C Days, Almost No Rain, 2–8 Rain Days/Month"

"visit the city October–April (dry, clear, 21–27°C days)… mild sunny days (21–27°C highs) and almost no rain… only 2–8 rain days a month"

Investigation summary

The Oct–Apr recommendation itself is sound and consistent with the data, but two summary numbers understate the edges of the window relative to the article's own table: April highs are 29–30°C (not ≤27°C), and October has up to ~11 rain days (not ≤8).

Confidence: High— Discrepancy established from the article's own table vs its own summary text.

True

Claim 12: Xantolo Transition Weather — Valles October 31°C/114 mm vs November 28°C/41 mm; Nights 16–19°C; Capital Nights 6–12°C

"in Ciudad Valles, October still averages 31°C highs with 114 mm of rain, while November drops to 28°C and 41 mm… mild nights (16–19°C)… If you base in the capital those same nights run 6–12°C"

Investigation summary

All six figures match the SMN normals files exactly.

Sources (1)

Confidence: High— Exact primary-source matches.

View full original report

Fact-Check Investigation Report: Weather in San Luis Potosí — Month-by-Month Guide + Best Time to Visit (2026)

**Source Analyzed:** https://www.sanluisway.com/blog/san-luis-potosi-weather-best-time-to-visit

**Verification Date:** July 3, 2026

**Investigation Conducted By:** San Luis Way Fact-Check Team using AI-powered research agents

EXECUTIVE SUMMARY

**Total Claims Analyzed** | 12

Verified TRUE | 10 PARTIALLY TRUE | 2 Verified FALSE | 0 UNVERIFIABLE | 0 OUTDATED | 0

**Overall Reliability Score:** 9.3/10

**Confidence Level:** High — The article's core climate figures were verified directly against the primary source it cites: the SMN/CONAGUA 1991–2020 climate-normals TXT files for stations 24069, 24111 and 24012 (fetched from smn.conagua.gob.mx on July 3, 2026; files carry an emission date of June 26, 2026). Every spot-checked table value, both annual totals, the Ciudad Valles figures and the record-minima claims match the official files exactly. The two soft spots are attributional/presentational, not numerical: the Köppen subtype (BSh vs BSk) sits on a genuine classification boundary where the two Wikipedia language editions disagree, and the dry-season summary ("21–27°C days", "2–8 rain days") slightly understates April heat and October rain days relative to the article's own table.

DETAILED FINDINGS

CLAIM 1: Monthly Climate Table Ranges for the City (Stations 24069 + 24111)

**CLAIM:** City table shown as ranges across SMN stations 24069 and 24111 — e.g., January 21–22°C high / 4–7°C low / 13–14 mm; May 29–31°C / 12–14°C / 37–44 mm; August 26–28°C / 12–14°C / 48–55 mm / ~10 rain days; September 24–26°C / 75–82 mm / 13 rain days; December 21–23°C / 4–7°C / 7–8 mm

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** Five months (January, May, August, September, December) plus several others were spot-checked cell-by-cell against the two official SMN normals files. Every range is the correctly rounded envelope of the two stations' 1991–2020 normal values.

**EVIDENCE CHAIN:**

  • **Primary Source:** [SMN Normales 1991–2020, station 24069 San Luis Potosí (DGE)](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24069.txt) — Jan high 20.8 / low 6.5 / 13.6 mm; May 29.2 / 14.4 / 36.6 mm; Aug 25.6 / 14.0 / 55.3 mm / 9.9 rain days; Sep 24.0 / 81.8 mm / 13.0 rain days; Dec 21.2 / 7.0 / 7.7 mm
  • **Primary Source:** [SMN Normales 1991–2020, station 24111 San Luis Potosí (SMN)](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24111.txt) — Jan high 22.2 / low 3.8 / 13.1 mm; May 30.7 / 11.5 / 43.7 mm; Aug 27.5 / 11.9 / 48.3 mm / 10.2 rain days; Sep 26.0 / 74.8 mm / 13.1 rain days; Dec 22.8 / 4.3 / 7.0 mm
  • **Corroborating Source:** [Wikipedia (ES) — San Luis Potosí climate box (SMN 1951–2010)](https://es.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(ciudad)) — Jan max 20.6°C, May max 28.4°C, consistent with the 24069-side of the ranges

**DETAILED ANALYSIS:** Example: January highs 20.8°C (24069) and 22.2°C (24111) → published as "21–22"; May rain 36.6 and 43.7 mm → "37–44"; September rain days 13.0 and 13.1 → "13". All twelve months' highs, lows, rain totals and rain-day counts reduce to exactly the published ranges under standard rounding. No cherry-picking between stations was detected — the ranges consistently use both endpoints.

**CONFIDENCE:** High — Direct match to the primary government dataset the article cites.

CLAIM 2: Annual Rainfall 386–404 mm over 81–95 Rain Days

**CLAIM:** "Annual totals: 386–404 mm of rain over 81–95 rain days"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** The official annual normals are 404.4 mm / 95.3 rain days (station 24069) and 386.1 mm / 81.3 rain days (station 24111) — the published range is exact.

**EVIDENCE CHAIN:**

  • **Primary Source:** [SMN station 24069](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24069.txt) — PRECIPITACIÓN NORMAL ANUAL 404.4 mm; DÍAS CON LLUVIA ANUAL 95.3
  • **Primary Source:** [SMN station 24111](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24111.txt) — PRECIPITACIÓN NORMAL ANUAL 386.1 mm; DÍAS CON LLUVIA ANUAL 81.3
  • **Corroborating Source:** [Wikipedia (EN) — San Luis Potosí (city)](https://en.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(city)) — cites ~392.1 mm annual precipitation (1951–2010 normals), inside the article's range

**CONFIDENCE:** High — Exact figures from primary source, independently consistent with the older normals period.

CLAIM 3: Ciudad Valles (Station 24012) — 36.0°C May Highs, 1,208.4 mm/Year, Extremes Near 48°C, 3× the Capital's Rain

**CLAIM:** "Ciudad Valles… average May highs of 36°C with recorded extremes near 48°C… 1,208 mm [annual rain]… three times the rain of the capital (1,208 mm vs ~400 mm a year)… summer nights that stay above 22°C"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** Every figure matches the official station 24012 file: May normal high 36.0°C, annual precipitation 1,208.4 mm, record daily maximum 48.0°C (April 27, 2011; 47°C also recorded in March and May), and June–August normal lows of 22.5–23.0°C. The 3× ratio holds (1,208.4 ÷ ~395 ≈ 3.1).

**EVIDENCE CHAIN:**

  • **Primary Source:** [SMN Normales 1991–2020, station 24012 Ciudad Valles](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24012.txt) — TEMPERATURA MÁXIMA NORMAL MAY 36.0; MÁXIMA DIARIA ABR 48 (27/2011); PRECIPITACIÓN ANUAL 1208.4; MÍNIMA NORMAL JUN 23.0 / JUL 22.5 / AGO 22.5; ALTITUD 87 msnm
  • **Corroborating Check:** All 36 cells of the article's Valles table (12 months × high/low/rain) were compared against the file — every value matches to the decimal (e.g., Jul 34.2 / 22.5 / 235.4; Sep 32.9 / 21.7 / 243.6)
  • **Corroborating Source:** SMN station metadata in same file — 87 m altitude, as stated in the article

**CONFIDENCE:** High — Full-table exact match to the primary source.

CLAIM 4: Station 24070 Excluded Because Its Series Is Unreliable

**CLAIM:** City figures use only stations 24069 and 24111; station 24070 (OBS) was excluded after its series showed implausible values (stated in the article's data notes/source methodology)

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** Station 24070's official normals file was fetched and compared. Its values are physically implausible relative to its neighbors and to independent references, so excluding it was the correct editorial call — and materially improves the article's accuracy.

**EVIDENCE CHAIN:**

  • **Primary Source:** [SMN Normales 1991–2020, station 24070 San Luis Potosí (OBS)](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24070.txt) — Jan normal high 24.5°C, May 34.4°C, annual precip 514.9 mm, only 57.8 rain days/year
  • **Counter-Comparison 1:** Stations 24069/24111 (2–5 km away, 30 m lower): Jan highs 20.8–22.2°C, May 29.2–30.7°C — 24070 runs 3.5–4.7°C warmer despite sitting 30 m HIGHER (1,903 m vs 1,870–1,871 m), which is physically backwards
  • **Counter-Comparison 2:** [Wikipedia (ES) climate box, SMN 1951–2010](https://es.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(ciudad)) — Jan max 20.6°C, May max 28.4°C — matches 24069/24111, contradicts 24070
  • **Internal Red Flags:** 24070 reports record daily maxima of 47°C (April and May) at 1,900 m altitude — values that mirror hot-lowland Ciudad Valles, not the altiplano; its rain-day count (57.8/yr) is 30–40% below both neighbors; and its "year of maximum" column clusters suspiciously in 2000–2001 across many months

**DETAILED ANALYSIS:** The inconsistency is real and severe. A 1,903 m station cannot plausibly average 34.4°C May highs when two stations 30 m lower and a few kilometers away average 29.2–30.7°C, and when the long-period (1951–2010) city normals agree with the lower figures. Had the article averaged all three stations, its table would have been skewed ~1.5°C warm. The exclusion is not data-shopping; it is quality control that independent references validate.

**CONFIDENCE:** High — The anomaly is visible in the primary file itself and confirmed by two independent comparison points.

CLAIM 5: Altitude — City at ~1,860–1,864 m; Stations at 1,870–1,903 m

**CLAIM:** "at roughly 1,860 m" / sources note: "Wikipedia (…1,864 m) and SMN station metadata (1,870–1,903 m)"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** All three altitude figures check out against their respective sources.

**EVIDENCE CHAIN:**

  • **Primary Source:** [Wikipedia (EN) — San Luis Potosí (city)](https://en.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(city)) — "1,864 meters (6,115 feet)"
  • **Primary Source:** SMN station files — 24069: ALTITUD 1870 msnm; 24111: 1871 msnm; 24070: 1903 msnm — exactly the "1,870–1,903 m" band the article cites
  • **Corroborating Source:** [Wikipedia (ES)](https://es.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(ciudad)) — "1864 m s. n. m."

**CONFIDENCE:** High — Exact matches on all figures.

CLAIM 6: Köppen Classification "BSh Semi-Arid" (Attributed to Wikipedia)

**CLAIM:** "Climate classification and altitude: Wikipedia (BSh semi-arid; 1,864 m)"

**VERDICT:** ⚠️ PARTIALLY TRUE

**INVESTIGATION SUMMARY:** "Semi-arid" is unambiguous, and Spanish Wikipedia does say BSh — so the attribution is technically sourced. But English Wikipedia classifies the city as BSk (cold semi-arid), and San Luis Way's own prior fact-check (SLP vs SMA) used BSk. The city sits exactly on the BSh/BSk boundary.

**EVIDENCE CHAIN:**

  • **Supporting Source:** [Wikipedia (ES) — San Luis Potosí (ciudad)](https://es.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(ciudad)) — "Semiárido cálido BSh (Estepario cálido)"
  • **Counter-Evidence:** [Wikipedia (EN) — San Luis Potosí (city)](https://en.wikipedia.org/wiki/San_Luis_Potos%C3%AD_(city)) — "features a cold semi-arid climate (BSk)"
  • **Primary Data Check:** SMN 1991–2020 mean annual temperature — 18.0°C (station 24069) and 17.6°C (station 24111). The Köppen h/k threshold is a mean annual temperature of 18°C: 24069 sits exactly on the line, 24111 falls on the BSk side

**DETAILED ANALYSIS:** This is a genuine edge case, not an invented fact: with station means of 17.6–18.0°C, the city straddles the 18°C isotherm that separates BSh from BSk, which is precisely why the two Wikipedia editions disagree. The article's practical description of the climate (semi-arid highland, hot days, cold nights) is unaffected. A more defensible phrasing would be "BSh/BSk boundary semi-arid" or simply "semi-arid (BS)". Flagged because a reader cross-checking against English Wikipedia will find an apparent contradiction.

**CONFIDENCE:** High (in the finding) — Both source texts and the underlying temperature data were checked directly.

CLAIM 7: WeatherSpark Sunshine Seasonality — Clear Season from ~Late October for ~7.7 Months; May Sunniest; September Most Overcast; Muggy ≈ Zero

**CLAIM:** "Per WeatherSpark, the clearer part of the year starts around late October and lasts about 7.7 months, May is the sunniest month, September the most overcast — and muggy humidity is essentially zero year-round"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** Fetched the cited WeatherSpark page; all four sub-claims match its published text almost verbatim.

**EVIDENCE CHAIN:**

  • **Primary Source:** [WeatherSpark — Average Weather in San Luis Potosí](https://weatherspark.com/y/5131/Average-Weather-in-San-Luis-Potos%C3%AD-Mexico-Year-Round) — clearer part of the year "begins around October 26 and lasts for 7.7 months, ending around June 18"; May is "the clearest month of the year" (clear ~65% of the time) and also the hottest; September is "the cloudiest month of the year" (overcast 73% of the time); humidity comfort level "a virtually constant 0% throughout" the year
  • **Cross-Check:** SMN normals corroborate the same seasonality independently — September has the most rain days (13.0–13.1) and highest rainfall; May has the highest normal maximum temperature (29.2–30.7°C)

**DETAILED ANALYSIS:** The article correctly labels WeatherSpark as "modeled data," which is honest sourcing — WeatherSpark reconstructs from reanalysis models rather than the SMN gauges. The intro's looser "300+ days of high-desert sun" is a promotional gloss not directly stated by WeatherSpark (which reports percent-of-sky metrics, not sunny-day counts), but it is directionally consistent with a 0%-muggy, majority-clear climate and is not presented as a sourced statistic.

**CONFIDENCE:** High — Direct quote-level match with the cited page.

CLAIM 8: Frost and Record Minima — Sub-Zero Lows Every Month October–March; −8°C (Jan) and −8.5°C (Dec) at Station 24111

**CLAIM:** "SMN station records show sub-zero minima in every month from October through March (down to −8°C in January and −8.5°C in December at station 24111)"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** The MÍNIMA DIARIA row of station 24111's normals file shows exactly these values.

**EVIDENCE CHAIN:**

  • **Primary Source:** [SMN station 24111](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24111.txt) — record daily minima: Oct −3.0, Nov −6.0, Dec −8.5 (Dec 14, 1997), Jan −8.0 (Jan 18, 2006), Feb −5.0, Mar −5.1 — sub-zero in all six months, exactly as claimed
  • **Corroborating Source:** [SMN station 24069](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24069.txt) — independently shows sub-zero record minima in Nov (−2), Dec (−5), Jan (−5), Feb (−4), Mar (−1); October's record there is +2°C, but the claim is correctly scoped to "SMN station records" collectively and 24111 covers October at −3

**DETAILED ANALYSIS:** The related packing advice (15–17°C daily swing) also checks out: normal high-minus-low spreads at the two stations run 12.8–18.4°C depending on month and station, centering in the claimed band during the dry season.

**CONFIDENCE:** High — Values read directly from the primary file.

CLAIM 9: Tamul Waterfall Nearly Dry in Early 2024 and Again in April–May 2026

**CLAIM:** "Tamul waterfall was reported nearly dry in early 2024 and again in April–May 2026 (upstream irrigation extraction plus heat, per La Jornada)"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** Both episodes are documented by dated regional and national press, and the attribution (irrigation extraction + heat) matches the reporting. Notably, this article adopts the recurring-risk framing that our own earlier Huasteca-itinerary fact-check demanded — the 2026 recurrence is disclosed, not buried.

**EVIDENCE CHAIN:**

  • **Primary Source (2024):** [La Jornada — Ayer y hoy de la cascada de Tamul en la Huasteca potosina (Feb 25, 2024)](https://www.jornada.com.mx/noticia/2024/02/25/estados/ayer-y-hoy-de-la-cascada-de-tamul-en-la-huasteca-potosina-5509)
  • **Corroborating Source (2024):** [El Sol de San Luis — Cascada de Tamul se seca por riego agrícola; exigen suspensión a Conagua](https://oem.com.mx/elsoldesanluis/local/cascada-de-tamul-se-seca-por-riego-agricola-exigen-suspension-a-conagua-29690750)
  • **Primary Source (2026):** [La Jornada — Extracción para riego y altas temperaturas secan la cascada de Tamul (May 6, 2026)](https://www.jornada.com.mx/noticia/2026/05/06/estados/extraccion-para-riego-y-altas-temperaturas-secan-la-cascada-de-tamul)
  • **Corroborating Source (2026):** [Potosinoticias — Se seca la cascada de Tamul por extracción de agua (Apr 27, 2026)](https://potosinoticias.com/2026/04/27/se-seca-la-cascada-de-tamul-por-extraccion-de-agua-urgen-intervencion-de-autoridades/)

**DETAILED ANALYSIS:** Dates, outlets and causal framing in the article match the source reporting exactly (La Jornada Feb 2024 and May 6, 2026; Potosinoticias Apr 27, 2026). The practical advice derived from it — temper April–May waterfall expectations, prefer November–March — follows logically from the evidence.

**CONFIDENCE:** High — Two independent outlets per episode, all dated.

CLAIM 10: FENAPO 2026 Runs August 7–30, and August Weather Fits the Fair Advice

**CLAIM:** "FENAPO 2026 runs August 7–30… 26–28°C days, 12–14°C nights and ~10 rain days in the month (48–55 mm total)"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** The dates match the official state portal and multiple national outlets (verified in depth in our FENAPO 2026 fact-check); the August climate figures match both SMN city stations.

**EVIDENCE CHAIN:**

  • **Primary Source:** [FENAPO — Gobierno del Estado de San Luis Potosí (official portal)](https://fenapo.slp.gob.mx/) — August 7–30, 2026, Recinto Ferial
  • **Corroborating Source 1:** [Infobae — Fenapo 2026: cartel completo y fechas (May 27, 2026)](https://www.infobae.com/mexico/2026/05/27/fenapo-2026-cartel-completo-y-fechas-de-todos-los-artistas-que-se-presentaran-en-el-palenque-de-la-feria/) — Aug 7–30
  • **Corroborating Source 2:** [Milenio — Fenapo 2026 cartelera completa](https://www.milenio.com/espectaculos/musica/fenapo-2026-katy-perry-motley-crue-y-mas-cartelera-completa) — Aug 7–30
  • **Primary Climate Data:** SMN stations 24069/24111 — August normals: highs 25.6/27.5°C, lows 14.0/11.9°C, rain 55.3/48.3 mm, rain days 9.9/10.2 — exactly "26–28°C / 12–14°C / 48–55 mm / ~10 rain days"

**CONFIDENCE:** High — Official portal plus multi-outlet corroboration for dates; primary data for weather.

CLAIM 11: Best-Time Verdicts — Internal Consistency of "Oct–Apr: 21–27°C Days, Almost No Rain, 2–8 Rain Days/Month"

**CLAIM:** "visit the city October–April (dry, clear, 21–27°C days)… mild sunny days (21–27°C highs) and almost no rain… only 2–8 rain days a month"

**VERDICT:** ⚠️ PARTIALLY TRUE

**INVESTIGATION SUMMARY:** The Oct–Apr recommendation itself is sound and consistent with the data, but two summary numbers understate the edges of the window relative to the article's own table: April highs are 29–30°C (not ≤27°C), and October has up to ~11 rain days (not ≤8).

**EVIDENCE CHAIN:**

  • **Internal Check (temperature):** The article's own table gives April highs of "29–30" (SMN: 28.6/30.0°C) — outside the "21–27°C days" band quoted in the short-answer box and FAQ. October–March highs (21–27) do fit the band
  • **Internal Check (rain days):** The table gives October "8–11" rain days (SMN: 10.6 at 24069, 7.9 at 24111) — above the "only 2–8 rain days a month" claim in the city card. November–April do fit (2.4–8.5)
  • **Supporting Data:** Rainfall totals Oct–Apr run 7–33 mm/month — "almost no rain" is fair for Nov–Apr (7–15 mm) and defensible for October (31–33 mm, fading)

**DETAILED ANALYSIS:** These are boundary-month generalizations, not fabrications: the 21–27°C figure accurately describes October–March and the 2–8 rain days figure accurately describes November–April, but each is presented as covering the full Oct–Apr window. The rest of the verdicts are internally consistent — May flagged as hottest/sunniest with storms only at the end (matches SMN May rain of 37–44 mm concentrated late and WeatherSpark's May-clearest finding), Huasteca Nov–Mar sweet spot consistent with the Valles rain curve and Tamul reporting, and the FENAPO/August advice matches the table exactly. A one-word fix ("21–27°C days through March; April hits 29–30°C") would resolve the discrepancy.

**CONFIDENCE:** High — Discrepancy established from the article's own table vs its own summary text.

CLAIM 12: Xantolo Transition Weather — Valles October 31°C/114 mm vs November 28°C/41 mm; Nights 16–19°C; Capital Nights 6–12°C

**CLAIM:** "in Ciudad Valles, October still averages 31°C highs with 114 mm of rain, while November drops to 28°C and 41 mm… mild nights (16–19°C)… If you base in the capital those same nights run 6–12°C"

**VERDICT:** ✅ TRUE

**INVESTIGATION SUMMARY:** All six figures match the SMN normals files exactly.

**EVIDENCE CHAIN:**

  • **Primary Source:** [SMN station 24012 Ciudad Valles](https://smn.conagua.gob.mx/tools/RESOURCES/Normales_Climatologicas/Normales9120/slp/nor9120_24012.txt) — Oct: high 31.1°C, rain 113.9 mm, low 19.3°C; Nov: high 28.2°C, rain 41.4 mm, low 16.1°C — matching "31°C/114 mm", "28°C/41 mm" and nights "16–19°C"
  • **Primary Source:** SMN stations 24069/24111 — Oct lows 11.5/9.3°C, Nov lows 9.0/6.4°C — matching the capital's "6–12°C" nights
  • **Corroborating Logic:** The claim that Xantolo (late Oct–early Nov) lands "right as the rains switch off" is supported by the Valles rain drop from 113.9 mm (Oct) to 41.4 mm (Nov)

**CONFIDENCE:** High — Exact primary-source matches.

PATTERN ANALYSIS

ACCURACY PATTERNS

This is the most rigorously sourced article we have fact-checked on the site to date. The core dataset — 96 city-table cells plus 36 Valles-table cells — reproduces the official SMN/CONAGUA 1991–2020 normals files without a single numerical error, and the decision to exclude station 24070 (whose normals are demonstrably anomalous) shows genuine data quality control rather than convenience averaging. Event claims (Tamul 2024/2026, FENAPO dates) reuse findings already verified in prior fact-checks and correctly incorporate that earlier criticism (the 2026 Tamul recurrence is now disclosed up front). The two imperfections are characteristic of travel-writing compression: a boundary-case Köppen subtype attributed to one Wikipedia edition when the other disagrees, and dry-season summary numbers that describe the core of the Oct–Apr window but not its edge months (April heat, October rain days).

BIAS INDICATORS

Mild pro-visit framing consistent with the publisher's mission ("300+ days of high-desert sun" is promotional gloss, not a sourced statistic), but the article is notably willing to publish anti-sales facts: near-freezing dawns, a wettest-month warning, the Tamul dry-ups, and explicit advice to temper April–May waterfall expectations. No evidence of figure-shopping — where the two stations disagree, both endpoints are shown as a range rather than the more flattering value.

SOURCING QUALITY

Exemplary for this genre: direct deep links to the specific SMN normals TXT files (retrievable, dated, primary), WeatherSpark explicitly labeled as modeled data, named and dated press citations for the Tamul episodes, and a stated caveat that normals are 30-year averages. The only sourcing weakness is the Wikipedia citation for the Köppen subtype, where the ES and EN editions conflict.

METHODOLOGY NOTES

SEARCHES CONDUCTED

  • Direct retrieval (July 3, 2026) of SMN/CONAGUA Normales9120 TXT files for stations 24069, 24111, 24012 and 24070 from smn.conagua.gob.mx (all four fetched successfully; emission date June 26, 2026)
  • Cell-by-cell comparison of the article's two climate tables (city ranges and Ciudad Valles) against the station files
  • Wikipedia EN and ES articles for San Luis Potosí (city): elevation, Köppen classification, 1951–2010 climate box
  • WeatherSpark year-round page for San Luis Potosí: clear-season dates, clearest/cloudiest months, humidity comfort
  • Cross-reference against San Luis Way's prior fact-checks: huasteca-potosina-itinerary-2026 (Tamul 2024/2026 sourcing) and fenapo-2026-artistas-cartel-completo (Aug 7–30 dates)
  • Köppen h/k boundary check (18°C mean annual temperature) computed from the stations' TEMPERATURA MEDIA rows

SOURCES CONSULTED

Tier 1 (Primary/Official): SMN/CONAGUA climate-normals files ×4, FENAPO official state portal — 5 sources Tier 2 (Established Media): La Jornada (×2), El Sol de San Luis, Potosinoticias, Infobae, Milenio — 6 sources Tier 4 (Modeled/Aggregator): WeatherSpark — 1 source Tier 6 (Encyclopedic): Wikipedia EN + ES — 2 sources

LIMITATIONS

  • Station 24070's unreliability was verified from its published normals (implausible values vs neighbors and independent references); the underlying raw year-by-year series was not re-downloaded, so the specific phrase "year-to-year jumps" rests on the normals-level evidence plus the internal red flags noted in Claim 4
  • WeatherSpark figures are model-derived; they corroborate but do not independently measure the SMN gauge data
  • Climate normals are 30-year averages — any specific travel year can deviate substantially, as the article itself warns
  • The "300+ days of sun" intro phrase has no direct statistical source and was assessed as promotional framing rather than a checkable claim

**VERIFICATION DATE:** July 3, 2026

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