For most of the country, March is a windy month of transition from winter to spring.
For Denver, March is a month of snowstorms and wild temperature swings. In fact, Denver’s snowiest month of the year, on average, is March. Denver averages 11.4 inches of snow during the third month of the year.
So why is March so snowy in Denver and along the Front Range?
There are several reasons, but one big one sticks out: In general, Denver is more susceptible to a big snow storm in March, and those storms tend to boost the monthly average. March is usually a boom-or-bust type of month for snowfall in Denver.
Consider this: In 136 years of Denver weather records, 56 March months have either had more than double or less than half of the month’s average snowfall of 11.4 inches. In other words, more than 40 percent of the time, Denver either finishes way above or way below its “normal” March number.
In those 136 years of official weather records, Denver has recorded 10 months with 30 or more inches of snowfall. Four of those have come in March — more than any other month.
At the same time, Denver has had 44 March months with 5.6 inches or less of snowfall. That’s almost a third that receive less than half of the monthly average snowfall.
With the boom-or-bust nature of spring snow in mind, it’s probably worth mentioning why storms tend to be especially powerful this time of year. Big storms tend to form during the spring months due to an increasing clash of temperatures. Though colder, Arctic air typically begins its annual retreat back to the North Pole during March, there is still plenty of cold air hanging around in late winter and early spring across the Northern Hemisphere.
In response to increased sunlight, however, warmer pushes of air from the south begin to infiltrate the southern United States more frequently. Those same warmer pushes of air increase during April and May, also leading to heightened chances for severe weather for Colorado and much of the Plains. Also, those sharp air mass clashes tend to create sharper pressure gradients, which leads to windier than usual weather for much of the country.
Critically, though, those increased temperature differences help to crank the jet stream, the all-important narrow ribbon of strong winds in the upper levels of the atmosphere. A volatile jet stream can help form strong areas of low pressure, such as last week’s historic bomb cyclone.
But in March, there’s usually just enough cold air hanging around Colorado that heavy, wet snow events can be fueled by these strong lows. For snow lovers, it’s the perfect sweet spot of stormy weather coupled with cold air. Though April is Denver’s second snowiest month on average, it usually starts to get a bit too warm for big snows, especially by the end of the month.
As we mentioned at the start of the month, this March has trended colder and snowier for some time. Denver has received 11.4 inches of snowfall so far this month – oddly enough, the exact March snowfall average.