I’ve had a couple of people ask my why there seems to be a greater snowfall in Colorado during March and early April than during the heart of the Winter in December and January. Fort Collins receives an average of 12.4 inches of snow in March, compared to only 7.1 inches in December.

Warm air can hold more water than cold air. Anyone who has experienced a hot and muggy day knows this. Also, warmer temperatures are more likely to evaporate more water into the air.

Snow requires cold air, so that the moisture that comes out of clouds is frozen instead of just rain.

The most snow fall comes when warm moist air with lots of water combines with cold frozen air that causes snow. This is most likely to occur during early spring months. During winter, the air is too cold on average to hold lots of water, and during summer, the air is too warm to cause it to snow. In the spring months in between, there are just the right amounts of both to make it snow more.

March 27, 2009. NASA image courtesy MODIS Rapid Response Team

The follow up question asks why it doesn’t rain more in the summer if warm air holds more water. Much of the warmer air is warm enough to hold onto the water causing it not to rain. If, however, the air is cooled, then water can fall out of those warm clouds as rain, just like squeezing a sponge.