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Mexico · Weekly

Week 40, 2026 (28 September – 4 October)

Final Issued 2026-10-11 · version 3 · Baseline 1991-2020 · next update 2026-10-21

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Version history (3)
  • version 3 · Final · 2026-10-11 — no change in the headline figures
  • version 2 · Final · 2026-10-11 — no change in the headline figures
  • version 1 · Final · 2026-10-11 — first issue

1 Key messages and climate synopsis

  • National mean temperature of 25.0 °C (+1.4 °C relative to 1991–2020): the warmest week 40 in the 1979–2026 series.
  • National precipitation of 41.6 mm, 183% of normal: the 3rd wettest week 40 in the 1979–2026 series.
  • The highest maximum temperature at GHCN stations was 39.6 °C at Colonia Juan Carras, Sin. on 2 October.
  • The largest 24-hour rainfall at GHCN stations was 141.0 mm at Tulancingo, Hgo. on 30 September.
  • 3 station records were broken (stations with at least 20 years of data).
  • Maximum temperature exceeded its 90th percentile on 40% of days (national mean; 10% expected).
  • Heat waves of national extent: 1; cold waves: 0.
  • 4 tropical cyclones passed within 300 km of the country; landfalls: Polo in Baja California Sur (category 2 hurricane).
  • El Niño conditions of very strong intensity in the equatorial Pacific (ONI JAS 2026: +2.2 °C).

Source: NOAA CPC / PSL

Mean temperature
25.0°C
+1.4 °C vs. normal (normal 23.6)
Above normal
1st warmest of 48 (1979–2026)
Maximum temperature
30.4°C
+1.3 °C vs. normal (normal 29.1)
Above normal
4th warmest of 48 (1979–2026) (tied with 1983)
Minimum temperature
19.6°C
+1.5 °C vs. normal (normal 18.2)
Above normal
1st warmest of 48 (1979–2026) (tied with 2009, 2023)
Precipitation
41.6mm
183% of normal (normal 22.8)
Much above normal
3rd wettest of 48 (1979–2026)
Station records
3

Source: NOAA CPC / PSL

2 Global and regional climate drivers

Sea-surface temperature anomaly in the Niño regions (°C)

RegionAnomaly (°C)Change from preceding period (°C)
Niño 1+25.30.6
Niño 34.00.1
Niño 3.43.20.1
Niño 41.20.1

Weekly mean (OISST v2.1)

Source: NOAA CPC

El Niño conditions of very strong intensity: the Oceanic Niño Index (ONI) for JAS 2026 was +2.2 °C.

Source: NOAA CPC

Monthly Niño 3.4 anomaly, last 24 months (°C)

Monthly Niño 3.4 anomaly, last 24 months (°C)

Source: NOAA CPC

MJO phase diagram (real-time OMI)

MJO phase diagram (real-time OMI)

Source: NOAA PSL

The Niño 3.4 anomaly was +3.20 °C (+0.10 °C relative to the preceding period).

The MJO was active on 7 of 7 days, most often in phase 2 (Indian Ocean); mean amplitude 1.2.

3 Precipitation

National precipitation
41.6mm
183% of normal (normal 22.8)
Much above normal
3rd wettest of 48 (1979–2026)

Source: NOAA CPC / PSL

Accumulated precipitation

Accumulated precipitation

Source: NOAA CPC / PSL

Percent of normal precipitation (1991–2020)

Percent of normal precipitation (1991–2020)

Source: NOAA CPC / PSL

Precipitation by region

RegionTotal (mm)Normal (mm)Difference (%)Category
Northwest28.85.8395.6Much above normal
North27.37.4271.3Much above normal
Northeast70.020.3245.4Much above normal
North-central50.814.2259.2Much above normal
West-central39.124.162.4Much above normal
Central53.033.259.7Above normal
South60.252.913.8Near normal
East55.369.4−20.3Below normal
Yucatán Peninsula48.047.31.6Near normal

Source: NOAA CPC / PSL

Stations with the largest precipitation excess

RegionStateStationAltitude (m)Anomaly (%)
NorthDurangoDurango1872.01906.0
SouthChiapasFrancisco Sarabia1052.01063.2
NorthCoahuilaSaltillo1790.0997.0
NorthwestBaja California SurLa Paz (City)18.0940.1
NorthChihuahuaTemosachi (Obs)1932.0828.7
North-centralSan Luis PotosíRio Verde983.0687.7
EastVeracruzHacienda Ylang Ylang Veracruz16.0280.1
EastVeracruzJalapa1389.0249.8
NorthChihuahuaHidalgo Del Parral1661.0225.8
NortheastTamaulipasCiudad Victoria355.0182.8

Source: NOAA NCEI

Stations with the largest precipitation deficit

RegionStateStationAltitude (m)Anomaly (%)
NorthwestBaja CaliforniaEjido Nuevo Leon (Obs)11.0−68.6

Source: NOAA NCEI

Largest 24-hour rainfall at stations

StationStateMax 24 h rainfall (mm)Date
TulancingoHidalgo141.02026-09-30
ManzanilloColima138.52026-09-30
TapachulaChiapas107.72026-10-03
Puerto AngelOaxaca105.92026-10-02
DurangoDurango99.22026-10-03
Tuxpan.Ver.Veracruz96.02026-09-30
Huajuapan De Leon (Dge)Oaxaca95.82026-10-03
OrizabaVeracruz94.12026-09-30
Francisco SarabiaChiapas89.52026-10-02
Hacienda Ylang Ylang VeracruzVeracruz80.32026-10-03

Source: NOAA NCEI

Daily national mean precipitation

Daily national mean precipitation

Source: NOAA CPC / PSL

National accumulated precipitation was 41.6 mm, 183% of the 1991–2020 average (22.8 mm), category “Much above normal”. It was the 3rd wettest week 40 in the 1979–2026 series.

The region with the highest percentage of normal was Northwest (496%) and the lowest was East (80%).

The largest daily grid-cell total was estimated on 1 October in — (124.3 mm).

Source: NOAA CPC / PSL

4 Temperature

Mean temperature
25.0°C
+1.4 °C vs. normal (normal 23.6)
Above normal
1st warmest of 48 (1979–2026)

Source: NOAA CPC / PSL

Mean temperature

Mean temperature

Source: NOAA CPC / PSL

Mean temperature anomaly (1991–2020)

Mean temperature anomaly (1991–2020)

Source: NOAA CPC / PSL

The national mean temperature was 25.0 °C, 1.4 °C above the 1991–2020 average (23.6 °C), category “Above normal”. It was the warmest week 40 in the 1979–2026 series.

By region, the largest anomaly was in Northeast (+3.0 °C) and the smallest in North (+0.6 °C).

Source: NOAA CPC / PSL

Maximum temperature
30.4°C
+1.3 °C vs. normal (normal 29.1)
Above normal
4th warmest of 48 (1979–2026) (tied with 1983)

Source: NOAA CPC / PSL

Maximum temperature anomaly (1991–2020)

Maximum temperature anomaly (1991–2020)

Source: NOAA CPC / PSL

Daily national maximum temperature

Daily national maximum temperature

Source: NOAA CPC / PSL

The national maximum temperature was 30.4 °C, 1.3 °C above the 1991–2020 average (29.1 °C), category “Above normal”. It was the 4th warmest week 40 in the 1979–2026 series (tied with 1983).

By region, the largest anomaly was in East (+3.6 °C) and the smallest in North (−0.7 °C).

Source: NOAA CPC / PSL

Minimum temperature
19.6°C
+1.5 °C vs. normal (normal 18.2)
Above normal
1st warmest of 48 (1979–2026) (tied with 2009, 2023)

Source: NOAA CPC / PSL

Minimum temperature anomaly (1991–2020)

Minimum temperature anomaly (1991–2020)

Source: NOAA CPC / PSL

Daily national minimum temperature

Daily national minimum temperature

Source: NOAA CPC / PSL

The national minimum temperature was 19.6 °C, 1.5 °C above the 1991–2020 average (18.2 °C), category “Above normal”. It was the warmest week 40 in the 1979–2026 series (tied with 2009, 2023).

By region, the largest anomaly was in Northeast (+3.3 °C) and the smallest in South (+0.5 °C).

Source: NOAA CPC / PSL

5 Climate extremes and records

Highest maximum temperature
39.6°C
Colonia Juan Carras, Sin. · 2026-10-02
Highest 24 h rainfall
141.0mm
Tulancingo, Hgo. · 2026-09-30

Source: NOAA NCEI

Highest maximum temperature by state

StateStationTemperature (°C)Date
SinaloaColonia Juan Carras39.62026-10-02
TlaxcalaTlaxcala De Xicontecatl (Dge)34.82026-09-30

Source: NOAA NCEI

Station records broken

StationStateVariableNew valueDatePrevious recordPrevious date
Colonia Juan CarrasSinaloaHighest maximum temperature39.62026-10-0238.01983-10-15
TulancingoHidalgoHighest 24 h rainfall141.02026-09-30100.61999-10-05
Tlaxcala De Xicontecatl (Dge)TlaxcalaHighest maximum temperature34.82026-09-3032.21969-10-03

Most extreme daily value of the period against the same period in all earlier years of record (at least 20 years; for weeks, the same calendar month).

Source: NOAA NCEI

Climate-extremes indices (national mean)

IndexDescriptionValueNormalDifferenceUnit
TX90pWarm days (Tmax > 90th percentile)40.110.030.1%
TN90pWarm nights (Tmin > 90th percentile)23.810.013.8%
TX10pCool days (Tmax < 10th percentile)14.010.04.0%
TN10pCold nights (Tmin < 10th percentile)0.710.0−9.3%
FDFrost days (Tmin < 0 °C)0.00.0−0.0d
SUSummer days (Tmax > 25 °C)5.95.60.2d
TRTropical nights (Tmin > 20 °C)3.42.70.7d
WSDIWarm spell days (≥ 6 days)0.1——d
CSDICold spell days (≥ 6 days)0.0——d
Rx1dayMaximum 1-day precipitation21.911.710.2mm
Rx5dayMaximum 5-day precipitation38.220.917.4mm
CDDConsecutive dry days (< 1 mm)2.64.4−1.8d
CWDConsecutive wet days (≥ 1 mm)3.01.71.3d

Percentile indices relative to calendar-day percentiles of 1991–2020 (5-day window); counts and maxima averaged over the country's grid cells.

Source: NOAA CPC / PSL

Heat and cold waves

DatesTypeDetails
2026-09-28 – 2026-09-30Heat waveUp to 67% of the country above the 90th percentile of Tmax. Regions: North, Northeast, North-central, West-central, Central, South, East and Yucatán Peninsula.

Wave: at least 3 consecutive days with at least half of the country above the 90th percentile of maximum temperature (heat) or below the 10th percentile of minimum temperature (cold). At most the 10 most intense are listed.

Source: NOAA CPC / PSL

6 Drought

The SPI is computed from monthly totals; see the latest monthly report (SPI).

7 Severe weather and notable events

Tracks of nearby tropical cyclones

Tracks of nearby tropical cyclones
Whole tracks; Saffir–Simpson category from NHC/JTWC. Source: IBTrACS v04 (provisional for recent seasons).

Source: NOAA NCEI

Tropical cyclones within 300 km of the country

NameBasinPeak intensityMaximum wind (km/h)StartEndClosest approach (km)LandfallLandfall intensity
PoloEastern North PacificCategory 5 hurricane2872026-09-172026-09-300Baja California SurCategory 2 hurricane
RachelEastern North PacificCategory 3 hurricane1942026-09-252026-10-081——
SimonEastern North PacificTropical storm742026-10-042026-10-08295——
IsaiasNorth AtlanticTropical storm1112026-10-042026-10-0894——

Source: NOAA NCEI

Notable events

DatesTypeDetails
2026-04-21 – 2026-10-09DroughtGDACS Orange alert: Drought in The Bahamas, Belize, Costa Rica, Cuba, Dominican Republic, Guatemala, Honduras, Haiti, Mexico, Nicaragua, El Salvador.

GDACS alerts and station rainfall of 150 mm or more in 24 hours (after quality control).

Source: GDACS

Tropical cyclones within 300 km of the country: 4 (Polo, Rachel, Simon and Isaias).

Landfalls: Polo in Baja California Sur (category 2 hurricane).

9 Outlook

Weekly reports do not include a forecast yet; see the outlook in the latest monthly report (NMME seasonal forecast).

11 Glossary, methodology and sources

Anomaly: difference between the observed value and its 1991–2020 normal. Percent of normal: observed total divided by the normal, times 100. Station record: most extreme daily value for the same month in all earlier years of record (at least 20 years).

Temperature: CPC_TEMP (0.5° daily grid); mean temperature is (Tmax + Tmin)/2. Precipitation: CPC. National, regional and state averages are weighted by the area of each grid cell inside each polygon. Normals refer to 1991-2020; ranks compare values rounded to one decimal. Stations: GHCN-Daily (NOAA NCEI); values flagged by its quality control are discarded, as are daily values more than 5 robust standard deviations from the station median and variables whose monthly anomaly differs by more than 3 °C from the gridded analysis. Period means require at least 80% of days with data and station normals at least 20 complete years. This report is generated automatically and does not replace official information from the national meteorological service.

SourceProductLicenseCitation
NOAA CPCONI, Niño-region SST indices (OISST v2.1), NAO and AOPublic domain (NOAA)NOAA Climate Prediction Center climate indices.
NOAA CPC / PSLCPC Global Unified Gauge-Based Analysis of Daily Precipitation, 0.5°Public domain (NOAA)CPC Global Unified Precipitation data provided by NOAA PSL, Boulder, CO, USA.
NOAA CPC / PSLCPC Global Unified Temperature, daily 0.5°Public domain (NOAA)CPC Global Unified Temperature data provided by NOAA PSL, Boulder, CO, USA.
GDACSGlobal Disaster Alert and Coordination System event listSee provider terms—
NOAA NCEIGHCN-DailyPublic domain (NOAA)Menne et al. (2012), J. Atmos. Oceanic Technol., doi:10.1175/JTECH-D-11-00103.1
NOAA NCEIIBTrACS v04r01 tropical-cyclone best tracksPublic domain (NOAA)Knapp et al. (2010), Bull. Amer. Meteor. Soc., doi:10.1175/2009BAMS2755.1
NOAA PSLReal-time OLR MJO Index (ROMI)Public domain (NOAA)Kiladis et al. (2014), Mon. Wea. Rev., doi:10.1175/MWR-D-13-00301.1
geoBoundariesgeoBoundaries gbOpen (Instituto Nacional de Estadística y Geografía (INEGI))Creative Commons Attribution 3.0 Intergovernmental Organisations (CC BY 3.0 IGO)—

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