The January thaw

Marilylle Sovern/Flickr

Just when the winter weather seems unbearably cold and dreary, we often encounter one of life’s heart-warming little mysteries: the January thaw.

On average, January is the coldest month of the year in the Northern Hemisphere. But more often than not, we in the Northeast experience a brief respite, most often toward the end of the month — historically, between Jan. 25 and Feb. 5.

We are getting an early gift this year. After a weekend of snow and brutal, single-digit temperatures, the highs soared yesterday to a balmy 53 in Newark and 58 in Atlantic City. Today we’re looking for highs in the low 60s, and may even break some records. Next week doesn’t look too bad, either, with daytime temperatures mostly in the 50s. In January!

While the thaw came earlier than usual, it fit the pattern by following an especially strong cold snap. By official definition, January thaw occurs “when maximum temperatures are 10 degrees above normal for two or more consecutive days.” The most interesting thing about this weather phenomenon might be that, even in the 21st century, no one really knows why it happens.

Zane Stephens of the Utah Climate Center classifies the January thaw with Indian summer and the Arizona monsoon as “weather singularities,” events which occur on or about the same time of year with measurable statistical frequency.

The January thaw has origins in the folklore of New England, and modern science confirms that there’s something to it. A search of weather data dating back to 1895 revealed that the thaw arrived as expected in 56 out of 106 years, or slightly more than half the time.

But why? Theories focus on a northward shift of high pressure in the eastern United States, which brings in warmer air from the south. The thaw might be related to fluctuations in ocean water temperatures. It might be due to changes in the upper-level wind patterns… and it might not. Another theory drags in sunspot activity, but with no greater certainty.

Never mind the whys — that first thaw is always welcome, even if it is a tease. By yesterday, the snow from last weekend (almost 7 inches) had melted away in my yard, done in by rain and warmth.

Well, we knew this won’t last, and there’s still a lot of winter left. It will be back to the heavy coats, scarves and gloves soon, no doubt. I’ll take the thaw while it lasts. Don’t look a gift horse in the mouth, as they say.