Climate averages 1991–2020
San Antonio weather
in December.
A mild, moderately wet month: the 11th warmest and the 5th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a mild month in San Antonio: daytime highs average 17.5°C and nights cool to about 7.8°C. By daytime temperature it is the 11th warmest of the 12 months.
Expect about 63 mm of rain on roughly 8 days, which makes December a moderately wet month (the 5th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 10 h 18 min on an average December day.
The nearest other city in this atlas is New Braunfels (47 km away). In December its highs average 17.1°C, about as warm as San Antonio, with 67 mm of rain.
Among the 498 cities listed in the United States, San Antonio ranks joint 88th of 498 for the warmest December highs and joint 234th of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; San Antonio is 7.0°C warmer than that mean.
From December to January, average highs fall by 0.7°C to 16.9°C, and monthly rainfall falls from 63 mm to 57 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
San Antonio climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 16.9°C6.7°C | 6.7°C | 57 | 7.2 | 10.510 h |
| February | 19.3°C8.7°C | 8.7°C | 59 | 7.5 | 11.111 h |
| March | 22.8°C12.1°C | 12.1°C | 79 | 9.2 | 12.012 h |
| April | 26.6°C15.7°C | 15.7°C | 78 | 8.5 | 12.913 h |
| May | 29.9°C19.9°C | 19.9°C | 103 | 11.2 | 13.614 h |
| June | 33.0°C23.1°C | 23.1°C | 69 | 9.5 | 14.014 h |
| July | 34.5°C24.1°C | 24.1°C | 50 | 6.1 | 13.814 h |
| August | 35.1°C24.7°C | 24.7°C | 50 | 5.8 | 13.213 h |
| September | 31.6°C22.0°C | 22.0°C | 77 | 8.6 | 12.412 h |
| October | 27.3°C17.3°C | 17.3°C | 83 | 7.7 | 11.511 h |
| November | 21.5°C11.7°C | 11.7°C | 67 | 7.2 | 10.711 h |
| December, selected | 17.5°C7.8°C | 7.8°C | 63 | 7.5 | 10.310 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- New Braunfels in DecemberUnited States · 47 kmHigh 17.1°C · Low 7.6°C · 67 mm rain
- Austin in DecemberUnited States · 118 kmHigh 16.6°C · Low 6.9°C · 70 mm rain
- Round Rock in DecemberUnited States · 144 kmHigh 16.3°C · Low 6.8°C · 70 mm rain
- Killeen in DecemberUnited States · 202 kmHigh 15.6°C · Low 5.9°C · 72 mm rain
- Corpus Christi in DecemberUnited States · 210 kmHigh 19.8°C · Low 11.7°C · 51 mm rain
- Piedras Negras in DecemberMexico · 213 kmHigh 19.1°C · Low 8.5°C · 27 mm rain
- Temple in DecemberUnited States · 216 kmHigh 15.6°C · Low 6.0°C · 82 mm rain
- Ciudad Acuña in DecemberMexico · 238 kmHigh 18.3°C · Low 7.8°C · 22 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for San Antonio) is explained once on the San Antonio year overview and on the Sources, method and limits page.