Weather in San Antonio in December

Prime time. December is about as good as San Antonio gets. Highs average 18.7 °C, lows 6.2 °C, and rain falls on 6 days — nothing in the month is working against you.

December ranks 4 of 12 in San Antonio: past the worst of the year but short of February, which is the month to book if the dates are open.

Rain falls on only 6 days, so an itinerary with no wet-weather fallback is a reasonable risk. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

Averages flatten a month, and this one hides a few things: it never really gets hot: not one day in an average December reaches 30 °C. Across the twenty years measured, the hottest December day reached 29.5 °C and the coldest night fell to -4.3 °C, and the wettest single day dropped 50 mm — roughly 111% of the month's rain in one day.

This is the volatile part. December rainfall has ranged from 3 mm to 119 mm across the twenty years measured — a 116 mm spread around an average of 45 mm. The average is real but almost no individual December looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind is light at 9.5 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 69%.

How December sits in the year

Temperatures hold steady either side: 23.2 °C in November, 18.7 here, 17.7 in January. Nothing about the timing within the month matters much.

Daylight in December

December sits at the dark end of San Antonio's year — 10.3 hours of daylight against 14 at midsummer, holding steady all month. Sightseeing days are genuinely shorter, and an itinerary built for summer will not fit.

An inland climate

With no coast nearby, the year swings a fair way — 31.5 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in San Antonio versus nearby

If San Antonio is one option among several, the nearby comparison is worth making. Corpus Christi is close enough to be a coin toss — 2.3 °C warmer, 1 day less rain. Laredo is a better bet in December — 2.9 °C warmer, 2 days less rain.

So: December works, with February the better month by 8 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in San Antonio

See all twelve months in San Antonio, or where else to go in December.