Fall First Frost/Freeze Statistics

Wondering how long the growing season lasts in your area? Here are some statistics for select climate sites in southeast Wyoming and western Nebraska with long records. These statistics are all based on records from 1951-2022. 

We have included the earliest date in the fall below select temperature thresholds, as well as the 10th, 50th, and 90th percentiles, and the latest first instance of a temperature below each threshold. 

To help interpret these values, we'll describe an example. Cheyenne's earliest first freeze (<=32F) in the autumn season came on September 7. The 10th percentile is September 13, which means that in 10% of years, the first freeze has already occurred by September 13 (whereas in 90% of years, it occurred after this date). The 50th percentile is September 28, which means that half of all years in the record had a freeze before this date, while half waited until after for the first freeze. The 90th percentile is October 14, which means that in 90% of years, the first freeze occurred on or before October 14, while only 10% waited until after. The latest first autumn freeze in Cheyenne (from 1951-2022) occurred on October 27. 

Cheyenne, WY

Laramie, WY

Rawlins, WY

Alliance, NE

Scottsbluff, NE

Chadron, NE

Sidney, NE