D.C.'s second-warmest December on record caps fifth-warmest year.
December was considerably drier than normal, but 2021, on the whole, had near-normal precipitation.
December felt more like an extension of autumn rather than the start of winter, and, indeed, Washington’s average temperature during the month was only 0.3 degrees colder than November.
The average temperature of 47.6 degrees ran a strong 5.9 degrees higher than normal and was second only to 2015 in records dating to 1871. We hit 70 twice and experienced several record-high low temperatures. The mercury sank below freezing only four times.
The mild December fit into a recent tendency for this month to be warm. Five of the 10 warmest Decembers on record have occurred since 2000.
The toasty December helped 2021 close as the fifth-warmest year on record in Washington.
https://www.washingtonpost.com/weather/2022/01/02/second-warmest-december-dc/?
