Animals know of the changing seasons by instinct. Our own awareness comes in many ways, but as the song goes, we in Washington on Friday didn’t “need a weatherman to know” our future included winter.

It’s not here yet. But the day’s cold and the early darkness banished doubt that the “times, they are a-changin’.”

A significant signal of the onset of cold times is the early setting of the sun. It went down in Washington on Friday, according to, at 5 p.m. On Saturday, for the first time this season, it will sink at 4:59 p.m.

In cold figures, the thermometer gave another indication of the vanishing of warmth and brightness. As of 4 p.m. Friday’s average temperature was 42 degrees, 10 below normal.

Not since May 13 had Washington fallen so far below normal.

Many people seemed to notice. Appropriate messages regarding the night’s high school football games appeared on social media.

“Extra ready for a cold night and a great game,“ tweeted Billie-Jean Bensen, the principal of Rockville High School. Her tweet showed a photo of two knit caps. In the District, where Phelps and Cardozo high schools met, Phelps’s principal tweeted that “We are chilly but cheering loudly.”

A bicyclist exhorted fellow pedalers to bundle up. Police in Bowie warned against warming up cars by letting them run unattended, lest they become targets of thieves. The library at Lake Braddock Secondary School in Fairfax County said the cold weather was “perfect for reading!