SAN ANTONIO – If you felt that this past December was abnormally warm in San Antonio, you’d be correct. In fact, an average temperature of 64.2° in December 2021 is the second-warmest December on record for the Alamo City, behind December of 1889 — before the escalator, radio, and paper clip were invented!
Usually the average December temperature — simply the average of the daily low and high — hovers right around 53.7° in San Antonio. But a lack of strong cold fronts during the month resulted in muggy, mild mornings and warm afternoons.
Take, for example, Wednesday, December 29. That’s when the thermometer reached a balmy 85°, smashing an all-time record high for the day.
The maximum temp in December 2021 averaged 74.1°, which is 9.8 degrees above normal!
What’s even more jarring is when you compare just how much warmer December 2021 to recent years. In the graphic at the top of the article, you can see the average temperature in December from 2001 to 2021.
Below, you can see the number of days (27!) that saw temperatures above average in the month of December.
Why so warm?
The primary reason for our unusually warm December is because La Niña conditions are ongoing in winter 2021-2022. La Niña is a climate pattern in the Pacific Ocean, which usually results in warmer, drier weather for South Central Texas.
That being said, climate change causes Texas temperatures to average about 2 degrees warmer than in the 20th century, thus giving December 2021 the “edge” ahead.
Dr. Nielsen-Gammon, the Texas State Climatologist, describes it best:
“Global warming didn’t cause this December to be record-setting, but it did contribute to the margin of victory.”