Last Saturday it was 44 degrees, yet it was snowing. How could this happen?
— Tony Tummimaro,
Temperatures must be 32 degrees or lower in the clouds where snowflakes form, but because flakes can fall more than 1,000 feet without melting, they can reach the ground with surface temperatures well above freezing. On Saturday, cloud-level temperatures hovered between 15 and 20 degrees.
Snow has fallen in Chicago on several occasions with temperatures in the mid-40s, though, like Saturday, the flakes immediately melted upon impact. One of the warmest recorded snowfalls was during the 1970s in Jacksonville, Fla., when flakes fell with an air temperature of 53. The air was extremely dry, and evaporative cooling from a burst of rain chilled the air enough to produce a brief period of snow and sleet.