This could be the snowiest day of the entire winter in New Jersey

Let it snow! With each passing week our weather is getting colder and colder. New Jersey’s first snowflakes of the season are now visible. And the winter solstice is just over a month away. It’s time to seriously think about winter weather. More specifically: snow.

As I thought about the many uses of “bread and milk,” I became scientifically curious.

I was wondering if there is a day of the year that tends to have more snow than any other day on the calendar for New Jersey. Sure, there is an average “peak” of winter weather. (In fact, there are three different peaks—more on that in a moment.) But can we pinpoint a single day that represents the peak of New Jersey’s snow season?

In fact we can.

methodology

To complete this analysis, I queried the Applied Climate Information System, a repository of weather and climate data.

I specifically looked at exactly 50 years of snowfall data, from 1971 to 2020. (An admittedly arbitrary choice of recording period, but I wanted a healthy spread of snow observations both geographically and temporally.) Approximately 675 weather stations reported snow data in New Jersey during this period .

For the purposes of this project, I marked a calendar day as “snowy” if a single weather station in the state reported at least 1 inch of snowfall that day.

The snowiest day

There is actually a definitive answer here. Since snow was reported in 24 out of 50 years (1971-2020) – almost half – February 5th is the winner.

And what a funny coincidence: February 5th is also National Weatherman Day. The most important holiday of the whole year!

Second place is February 13th with 23 incidents. In third place is January 21st at 10 p.m. And in fourth place are January 19th, January 25th, February 4th and February 6th, each 21 times in 50 years.

A look at the statistics

We can even use snow data from all years and create a graph. This shows, for each day of New Jersey’s snow season (October 4 through May 9), the percentage of years from 1971 to 2020 in which at least one inch of snow was reported anywhere in New Jersey.

Day-to-day fluctuations are to be expected. This is explained by the red trend line, which represents a 14 point moving average (2 weeks). Some clear patterns can be seen here.

First, I would like to point out that the data set is fundamentally trimodal. This means there are three definite peaks of snowstorm activity. A small bump on snowy days around mid-December leading up to the winter solstice. Another occurs in mid- to late January and coincides with the coldest climatic temperatures of the year – “deep winter”. And another peak occurs in early to mid-February The highest bar on February 5th.

Overall, more than 2 inches of snow was observed in New Jersey on 178 of 366 days. That’s a whopping 49% of the year it snowed here.

If you look at our snow season from start to finish (i.e. from left to right in the graphic), it is clear that it is snowing may Autumn in November. However, snow of more than an inch of snow is fairly rare in New Jersey until December.

There is a significant minimum value on December 24th. Christmas Eve. Only four of the last 50 years have seen even an inch of magical Christmas Eve snow. However, there were 11 snow observations on Christmas Day. This strikes me as a strange outlier and makes me wonder whether there is some observational bias or other ambiguity in the reports here.

Due to Leap Day, you will notice another data minimum on February 29th. 4 of the 13 February 29ths during the survey period reported snow. That’s about 30%, which is consistent with other dates nearby in late February and early March.

Finally, it’s remarkable how quickly the chance of snow decreases beyond the first day of spring, around March 21st. Snow in April is about as rare as November at either end of the graph.

Final thoughts

Obviously, every winter season in New Jersey is different. And this climatological analysis in no way serves as a short or long term forecast. Just a nice little research that proves that common sense largely agrees with reality when it comes to when New Jersey has the highest chance of snow.

So stock up on road salt, put on your pajamas inside out, and start making hot chocolate. February 5th could be a wintry day!

Dan Zarrow is chief meteorologist at Townsquare Media New Jersey. Check out Dan’s weather blog or follow him on Facebook for the latest weather forecasts.