Spring Last Frost/Freeze Statistics

Wondering when it's safe to plant frost sensitive vegetation across our 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 1951-2025. 

For several temperature thresholds important to growers, we have included the earliest last date colder than the threshold, the 10th, 50th, and 90th percentile dates, and the latest date colder than the threshold. The percentiles can be interpreted as the probability of having seen the last instance colder than a threshold by a certain date.

For example, the 10th percentile last freeze (<32F) date for Cheyenne is April 30. That means that there is a 10% chance that the last freeze date has already occurred by April 30, and conversely a 90% chance an additional freeze occurs after that date. The 50th percentile date is May 13th, which means there is a 50% chance that the last freeze has already occurred by that date. Lastly, the 90th percentile date is May 25th, which means that there is a 90% chance that the last freeze has already occurred by May 25th. 

 Cheyenne, WY

 Laramie, WY

 Rawlins, WY

Alliance, NE

Scottsbluff, NE

Chadron, NE

Sidney, NE