Frost dates for Casper 1Sw, WY
At this NOAA station the last spring frost (32°F) usually comes by May 12 and the first fall frost around October 1, giving a growing season of about 143 days.
May 12average last spring frost
October 1average first fall frost
JanAprJulOctDec
Frost odds
| 1 year in 10 the last spring frost is later than | May 26 |
| Half of years the last spring frost is later than | May 12 |
| 9 years in 10 the last spring frost is later than | April 28 |
| 1 year in 10 the first fall frost is earlier than | September 18 |
| Half of years the first fall frost is earlier than | October 1 |
| 9 years in 10 the first fall frost is earlier than | October 19 |
A hard freeze (28°F) usually ends by April 30 and returns around October 13.
A light frost (36°F, which can still nip tender plants) usually ends by May 24 and returns around September 23.
Station USC00481572, elevation 1568 m. Based on 5 years of 1991 to 2020 records. A garden higher up, in a hollow or far from this station can freeze later in spring.
Check another ZIP
Sources
- U.S. Annual/Seasonal Climate Normals, 1991 to 2020 (freeze probability dates by station), NOAA National Centers for Environmental Information, checked 1 November 2026
- Annual/Seasonal Normals 1991 to 2020 documentation, NOAA National Centers for Environmental Information, checked 1 November 2026
- 2024 Gazetteer Files, ZIP Code Tabulation Areas, US Census Bureau, checked 1 November 2026