Frost dates for St Marie, MT
At this NOAA station the last spring frost (32°F) usually comes by May 13 and the first fall frost around September 27, giving a growing season of about 134 days.
May 13average last spring frost
September 27average 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 13 |
| 9 years in 10 the last spring frost is later than | May 2 |
| 1 year in 10 the first fall frost is earlier than | September 13 |
| Half of years the first fall frost is earlier than | September 27 |
| 9 years in 10 the first fall frost is earlier than | October 9 |
A hard freeze (28°F) usually ends by May 3 and returns around October 5.
A light frost (36°F, which can still nip tender plants) usually ends by May 24 and returns around September 19.
Station USW00094010, elevation 840 m. Based on 25 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