Frost dates for Mt Diablo Junction, CA
At this NOAA station the last spring frost (32°F) usually comes by March 8 and the first fall frost around December 22, giving a growing season of about 282 days.
March 8average last spring frost
December 22average first fall frost
JanAprJulOctDec
Frost odds
| 1 year in 10 the last spring frost is later than | April 15 |
| Half of years the last spring frost is later than | March 8 |
| 9 years in 10 the last spring frost is later than | January 12 |
| 1 year in 10 the first fall frost is earlier than | November 23 |
| Half of years the first fall frost is earlier than | December 22 |
| 9 years in 10 the first fall frost is earlier than | February 11 |
A hard freeze (28°F) usually ends by February 8 and returns around January 16.
A light frost (36°F, which can still nip tender plants) usually ends by April 19 and returns around November 29.
Station USC00045915, elevation 661 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.
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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