Thode: Our Glorious January

Blogger's Note: Because I'm a Democrat, I can be pretty shitty with numbers. Steve Thode, in contrast, excels at numbers crunching. He was our go-to guy when COVID was at its worst. He both made sense of the data and pointed out numerous errors in how new cases and deaths were being reported. His latest post is about a more pedestrian subject - our mild winter (so far).   

As someone who grew up in Southern New Mexico where the skies are not cloudy all day and winters are wonderfully sunny and warm, winters in the Lehigh Valley can be tough on my psyche.

A little less so this January when temperatures were more like March.

Allow me to start by defining “winter.” Calendar winter (astronomical winter) runs from the Winter Solstice (December 21 give or take a day) until the Vernal Equinox (March 21 give or take a day). Solar winter (the three months with the least amount of daylight) runs from about November 5 to February 5. Again, give or take a day. Meteorological winter (the three coldest months) is December through February.

Let’s focus on meteorological winter.

According to the National Weather Service at LVIA, December typically has a monthly average temperature of 35.0 degrees; January typically has a monthly average temperature of 30.1 degrees; and, February typically has a monthly average temperature of 32.5 degrees. The “dead of winter” is between January 17 and January 28 when the typical daytime high is 38 degrees and the typical nighttime low is 21 degrees.

This winter, December came in a bit below normal at 32.9 degrees - primarily due to the polar vortex that paid us a visit at Christmastime. Christmas Eve was the coldest day in more than three years. However, once the polar vortex retreated north, temperatures warmed up nicely and stayed relatively pleasant throughout all of January.

In fact, at an average daily temperature of 38.2 degrees, January 2023 was the warmest January on record, besting the previous record of 37.1 degrees set in 1990. The winter of 1989-90 remains the one with the most extreme temperature change from December to January. For those of you old enough to remember, December of 1989 had a teeth-chattering, bone-rattling average temperature of 21.2 degrees - far and away the coldest December on record.

So, how did we set the new January record this year? It wasn’t necessarily because our days were quite warm, although we did have eight days with a high temperature in the 50s and one day with a high temperature in the 60s. It was more because our nights were not cold. The mercury dropped below 23 degrees on only one day - January 16. For the entire month, the average daily low temperature was more than 31 degrees. And we enjoyed 14 days where the temperature never dropped below freezing - including the first seven days of the month.

Why didn’t it get very cold on January nights? Clouds, clouds and more clouds. Overcast skies trap whatever heat is on the ground; clear skies allow that heat to escape. Likewise, partly cloudy or overcast skies during daylight hours stop much of the sun’s warmth from reaching the ground. For the entire month, there were only three clear days in the Lehigh Valley. The other 28 days were either partly cloudy or overcast. I’m guessing most of you already knew that! It also helped that the ground did not freeze all month and there was no snow covering the ground save for a few hours on January 25.

That helps explain why my boyhood hometown of Las Cruces, New Mexico - where more than 80% of January days have clear skies - had an average overnight low only about one degree higher than the Lehigh Valley, but also had an average daytime high 14 degrees warmer than the Lehigh Valley.

So, does this tell us anything about whether Punxsutawney Phil will see his shadow today? Of the five warmest Januarys since the turn of the century (2002, 2006, 2012, 2017 and 2020), only 2006 had a colder February than January. And only one - 2017 - had below normal temperatures for the month of March. But, that March was preceded by the warmest February on record.

Personally, I’m hoping it’s either overcast or a blizzard in Punxsutawney.