San Antonio climate — normals and trends
San Antonio (United States) has a humid subtropical climate (Cfa) under the Köppen-Geiger classification. Its mean annual temperature is 20.2 °C and it receives 791 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is August (28.7 °C on average) and the coldest is January (10.3 °C). Rainfall peaks in May.
San Antonio averages 10 frost days, 134 hot days (≥ 30 °C) and 101 rainy days per year.
San Antonio has warmed by +1.6 °C between 1940 and 2025, or +0.18 °C per decade. This trend is statistically significant.
The hottest day of the period reached 43.2 °C (on 28 August 2011) and the coldest -14.8 °C (on 31 January 1949).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
San AntonioTexas
- coords
- 29.42°, -98.49°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
20.2°C
Average daily high
26.0°C
Average daily low
15.2°C
Annual rainfall
791mm
Sunshine / day
9.4h
Mean relative humidity
68%
Average peak wind
17.8km/h
Seasonal range
18.4°C
Frost days (< 0 °C)
10 d/yr
Hot days (≥ 30 °C)
134 d/yr
Rainy days (≥ 1 mm)
101 d/yr
Annual snowfall
1.0 cm
Average feels-like high
26.4 °C
Average feels-like low
15.0 °C
Average peak gust
36.0 km/h
Tropical nights (≥ 20 °C)
138 d/yr
Solar radiation
17.3 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.6 °C
since 1940
+0.2 °C per decade · r² = 0.31 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
43.2 °C
28 August 2011
Coldest day
-14.8 °C
31 January 1949
Wettest day
157 mm
23 September 1957
Windiest day
53.0 km/h
11 September 1961
Strongest gust
112.3 km/h
11 September 1961
Hottest feels-like
44.9 °C
21 June 2023
Coldest feels-like
-19.5 °C
31 January 1949
Snowiest day
10.7 cm
12 January 1985
Sunniest day
13.3 h
5 July 1943
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 14.1 °C | -2.0 °C | 57 mm | +5 mm |
| Feb | 19.1 °C | +0.7 °C | 28 mm | -31 mm |
| Mar | 27.2 °C | +4.8 °C | 79 mm | +12 mm |
| Apr | 28.7 °C | +2.5 °C | 54 mm | -33 mm |
| May | 32.0 °C | +2.6 °C | 96 mm | -15 mm |
| Jun | 33.1 °C | +0.5 °C | 101 mm | +33 mm |
| Jul | 32.8 °C | -1.4 °C | 158 mm | +113 mm |
| Aug | 35.8 °C | +1.1 °C | 18 mm | -26 mm |
| Sep | 33.8 °C | +2.2 °C | 24 mm | -49 mm |
| Oct | 31.2 °C | +4.0 °C | 16 mm | -56 mm |
| Nov | 25.9 °C | +4.6 °C | 22 mm | -40 mm |
| Dec | 20.5 °C | +3.0 °C | 12 mm | -37 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of San Antonio?
San Antonio has a humid subtropical climate (Köppen Cfa). Over 1940-2025, the average annual temperature is 20.2 °C and it receives 791 mm of precipitation per year.
What is the hottest day ever recorded in San Antonio?
The hottest day measured in San Antonio between 1940 and 2025 was 28 August 2011, reaching 43.2 °C.
What is the coldest day in San Antonio?
The coldest day measured in San Antonio between 1940 and 2025 was 31 January 1949, at -14.8 °C.
Does it snow in San Antonio?
Almost never: San Antonio sees virtually no snow, with about 10 frost days per year.
Has the climate of San Antonio warmed?
Yes: San Antonio warmed by +1.6 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in San Antonio?
The wettest day measured in San Antonio between 1940 and 2025 was 23 September 1957, with 157 mm of rain in 24 hours.
What was the windiest day in San Antonio?
The windiest day measured in San Antonio between 1940 and 2025 was 11 September 1961, with winds reaching 53.0 km/h.
What is the warmest month in San Antonio?
The warmest month in San Antonio is August (28.7 °C on average); the coldest is January (10.3 °C).
How much does it rain in San Antonio?
San Antonio receives on average 791 mm of precipitation per year, spread over about 101 rainy days.
Is it sunny in San Antonio?
San Antonio gets on average 9.4 hours of sunshine per day, roughly 3,431 hours per year over 1940-2025.
What is the biggest single-day snowfall in San Antonio?
The heaviest 24-hour snowfall measured in San Antonio between 1940 and 2025 was 12 January 1985, with 10.7 cm.
Are there tropical nights in San Antonio?
Yes: San Antonio has on average 138 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in San Antonio?
In San Antonio, between 1940 and 2025, the highest apparent temperature reached 44.9 °C on 21 June 2023, and the lowest was -19.5 °C on 31 January 1949.
Compare San Antonio with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around San Antonio