Snow in September


Fall streaks descending from cirrus clouds over Cedar Falls, Iowa on September 17, 2017. These streamers are falling ice crystals in sub-freezing air high overhead. The surface temperature was 71 degrees so there was no threat of snow reaching the ground. In fact, the air mass was so dry that the precipitation sublimated - meaning the ice crystals changed directly from ice to vapor in the cold dry air aloft.

Cirrus are precipitating clouds - except the precipitation never reaches the ground. Check out the Weather Briefing Cloud ID Chart. You will see that cirrus are very high. Precipitation would need to fall several miles to reach the ground. It is simply too far to fall before disappearing into thin air as water vapor.