It was an unseasonably warm day for the New England Patriots Super Bowl victory parade on Feb. 5 in Boston. (Billie Weiss/Getty Images)

It was another day of springlike weather in early February as groundhog-bashers ate their words. Washington shot up to a record 74 degrees and Boston, celebrating the New England Patriots' Super Bowl win, tied its record of 65. Meanwhile, Philadelphia and New York City also hit the mid-60s. The unseasonable warmth will come to an end in most spots by Wednesday.

As rare as temperatures this high may seem for February, they’re not that unusual. That said, we are seeing a tendency toward more unusually warm winter days because of rising winter temperatures.

Setting aside climate change for a moment, winter thaws have always been present in the climate of the Northeast.

Washington, for example, averages 10 60 degree days every winter. Philadelphia and New York average six and three such days, respectively.

Meteorological winter runs from the start of December through February. Most years one or two days hit 70 in Washington. But in recent years, in Washington and elsewhere, those numbers seem to be increasing.

Washington’s Reagan National Airport saw six days topping 70 in February of 2017, including a record high of 77 on the 24th. The preseason taste of summer accelerated the cherry trees toward an early peak bloom.

That same day, Boston made it to 73 — only the second time on record that Logan International Airport saw a 70 in February. They managed it again almost exactly a year later, both on Feb. 20 and 21, 2018.

In recent years, we’ve even seen summertime heat on the East Coast in February. On Feb. 21 last year, Washington made it to 82, its warmest temperature so early in the calendar year on record. Three years earlier, the day had featured cold rain and just under three inches of sloppy snow.

The week of Feb. 21 for unknown reasons always seems to include a sudden warm-up in the Mid-Atlantic. In the past decade, six years have recorded 65 degree-plus temperatures in D.C. within three days of Feb. 21. Four of the six climbed above 73 degrees. While the “Indian summer” is used to describe the last fleeting warmth that lingers into autumn, maybe it’s time to invent a term for these early summer previews.

A number of these early-season warm-ups have brought a dramatic clash of seasons. On Feb. 23 to 24, 2016, a cold front met a particularly balmy air mass, spawning a line of tornadic supercells that swept through the Deep South and parts of the Eastern Seaboard. A swarm of deadly tornadoes — including two EF-3s — plowed through Virginia, accompanied by hail larger than baseballs in the town of Mecklenburg. The storms merged into a vicious squall line overnight, bringing an 83 mph wind gust to Boston — the strongest since Hurricane Sandy in 2012.

This year’s bout of warm days came with a little less fanfare, though it brought air quality concerns to Washington and triggered ice jams near Buffalo.

The mid- to late-week period will still be mild south of the Mason-Dixon Line, with 60s returning Thursday and Friday, but the Northeast will cool into the 30s and 40s. The cold front will bring periods of rain showers, with icing possible Thursday in interior New England.

The effect of climate change


(Climate Central)

While this thaw shares characteristics of those from the past, winter temperatures are warming, and the frequency and intensity of these thaws are increasing and are expected to do so further in the future.

The National Climate Assessment published in 2018 reported temperatures in winter have warmed three times as fast as in summer. “By the middle of this century, winters are projected to be milder still, with fewer cold extremes, particularly across inland and northern portions of the Northeast,” it said.

Jason Samenow contributed to this report.