San Antonio climate

Name: San Antonio
Address: US

San Antonio is warmest in August, with average highs of 35 °C, and coldest in January, when nights average 7.2 °C. May is the wettest month (111 mm) and August the driest (50 mm). Figures are 1991–2020 climate normals.

Across a full year San Antonio averages 861 mm of rain, 227 days above 25 °C and 4 days below freezing.

United States · 198 m elevation · population 1,526,656 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 35 °C
Coldest month January 7.2 °C
Driest month August 50 mm
Wettest month May 111 mm
Least cloud October 41 % cloud
Hottest on record August 43 °C
Coldest on record February -6.8 °C

What to expectSan Antonio through the year

San Antonio has a clear annual cycle: average daily highs run from 18 °C in January to 35 °C in August, a swing of 18 °C in mean temperature across the year.

Counted across a normal year, 227 days a year reach 25 °C, 140 of them reach 30 °C, 4 nights drop below freezing. The warmest reading in the 1991–2020 record is 43 °C, in August.

Rain is strongly seasonal. May averages 111 mm against 50 mm in August — 2.2 times as much. Planning around the dry months matters more here than planning around temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	17.6 °C	57 mm	55 %
February	20.2 °C	60 mm	57 %
March	23.5 °C	80 mm	57 %
April	27.2 °C	80 mm	55 %
May	30.2 °C	111 mm	57 %
June	33.1 °C	72 mm	47 %
July	34.6 °C	53 mm	45 %
August	35.2 °C	50 mm	42 %
September	31.8 °C	84 mm	44 %
October	27.7 °C	84 mm	41 %
November	22.0 °C	68 mm	50 %
December	18.1 °C	63 mm	55 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C	Days below 0 °C
January	17.6 °C	7.2 °C	11.5 °C	30.6 °C	-5.9 °C	1	0	2
February	20.2 °C	9.0 °C	13.6 °C	35.8 °C	-6.8 °C	5	0	1
March	23.5 °C	12.4 °C	17.1 °C	35.8 °C	-3.7 °C	13	1	0
April	27.2 °C	15.9 °C	20.8 °C	37.0 °C	2.2 °C	23	6	0
May	30.2 °C	20.0 °C	24.5 °C	37.7 °C	8.3 °C	29	16	0
June	33.1 °C	23.1 °C	27.7 °C	41.8 °C	15.7 °C	30	26	0
July	34.6 °C	24.1 °C	28.9 °C	41.6 °C	19.7 °C	31	29	0
August	35.2 °C	24.7 °C	29.5 °C	43.1 °C	18.8 °C	31	30	0
September	31.8 °C	22.1 °C	26.5 °C	42.6 °C	11.3 °C	29	22	0
October	27.7 °C	17.5 °C	22.0 °C	36.4 °C	1.6 °C	24	10	0
November	22.0 °C	12.2 °C	16.3 °C	32.1 °C	-2.8 °C	9	0	0
December	18.1 °C	8.2 °C	12.3 °C	28.4 °C	-5.0 °C	2	0	1

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind
January	57 mm	7	10 h/day	55 %	68 %	18 km/h
February	60 mm	8	11 h/day	57 %	68 %	19 km/h
March	80 mm	9	12 h/day	57 %	68 %	20 km/h
April	80 mm	9	13 h/day	55 %	68 %	20 km/h
May	111 mm	11	14 h/day	57 %	71 %	19 km/h
June	72 mm	10	14 h/day	47 %	69 %	18 km/h
July	53 mm	6	14 h/day	45 %	65 %	18 km/h
August	50 mm	6	13 h/day	42 %	62 %	17 km/h
September	84 mm	8	12 h/day	44 %	66 %	16 km/h
October	84 mm	8	11 h/day	41 %	66 %	17 km/h
November	68 mm	7	11 h/day	50 %	68 %	18 km/h
December	63 mm	8	10 h/day	55 %	69 %	18 km/h

How San Antonio compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
San Antonio	35 °C	7.2 °C	861 mm	227
Austin · United States	35 °C	6.3 °C	924 mm	216
Corpus Christi · United States	32 °C	12 °C	781 mm	215
Piedras Negras · Mexico	37 °C	8.0 °C	563 mm	259
Nuevo Laredo · Mexico	37 °C	10 °C	497 mm	281
Ciudad Acuña · Mexico	36 °C	7.3 °C	481 mm	248
Cypress · United States	34 °C	7.7 °C	1,173 mm	213

Where San Antonio ranks

Ranking	Position	Value
The warmest places in North America in August	18thof 50	35 °C
The warmest places in North America in July	27thof 50	35 °C
The warmest places in North America in June	30thof 50	33 °C
The warmest places in North America in September	35thof 50	32 °C

Planning a trip? See the best time to visit San Antonio.

QuestionsCommon questions about San Antonio’s climate

When is the best time to visit San Antonio?

That depends on what you want, so the honest answer is a comparison rather than a single month. March, April, October sit closest to 20 °C on average, August is the warmest month and August the driest. The month-by-month table above has the full picture.

How hot does San Antonio get?

In August, the warmest month, daily highs average 35 °C. About 140 days a year pass 30 °C. The highest value in the 1991–2020 record is 43 °C.

How cold does it get in winter?

Nights average 7.2 °C in January, the coldest month. A normal year has 4 nights below freezing.

Which month is wettest in San Antonio?

May, averaging 111 mm over 11 days with rain. The driest month is August with 50 mm. The year as a whole averages 861 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in San Antonio rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.