Frost dates for Boulder 14 W, CO
At this NOAA station the last spring frost (32°F) usually comes by June 21 and the first fall frost around September 2, giving a growing season of about 71 days.
June 21average last spring frost
September 2average first fall frost
JanAprJulOctDec
Frost odds
| 1 year in 10 the last spring frost is later than | July 4 |
| Half of years the last spring frost is later than | June 21 |
| 9 years in 10 the last spring frost is later than | June 7 |
| 1 year in 10 the first fall frost is earlier than | August 17 |
| Half of years the first fall frost is earlier than | September 2 |
| 9 years in 10 the first fall frost is earlier than | September 15 |
A hard freeze (28°F) usually ends by June 4 and returns around September 14.
Station USW00094075, elevation 2996 m. Based on 17 years of 1991 to 2020 records. A garden higher up, in a hollow or far from this station can freeze later in spring.
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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