Frost dates for Grass Valley #2, CA
At Grass Valley #2, the median last spring frost (32°F) is Apr 10 and the median first fall frost is Nov 13, for a typical growing season of 215 days. For a 90% chance that the last frost has passed, wait until Apr 30. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Apr 10Last spring frost (median)50% chance of 32°F after this date
- Apr 30Safer planting date10% chance of 32°F after this date
- Nov 13First fall frost (median)50% chance of 32°F by this date
- 215 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 13 | Apr 28 | May 20 |
| 32°F | Mar 17 | Apr 10 | Apr 30 |
| 28°F | Jan 31 | Mar 9 | Apr 8 |
| 24°F | Dec 19 | Jan 21 | Feb 27 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Oct 11 | Oct 31 | Nov 13 |
| 32°F | Oct 26 | Nov 13 | Dec 1 |
| 28°F | Nov 11 | Dec 1 | Dec 21 |
| 24°F | Nov 28 | Dec 19 | Jan 24 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 157 days | 182 days | 204 days |
| 32°F | 188 days | 215 days | 244 days |
| 28°F | 230 days | 268 days | 310 days |
| 24°F | 291 days | 336 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 84% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 95975 | 9a | 20 to 25°F | 8 km |
| 95946 | 9b | 25 to 30°F | 13 km |
| 95949 | 9b | 25 to 30°F | 13 km |
| 95977 | 9b | 25 to 30°F | 20 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00043573, at 39.2042, -121.0681, elevation 732 m (2,400 ft).
- Data quality: Standard (24+ years of data), 25 years of freeze data.
- Average days per year at or below 32°F: 61.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Nevada City (7 km)
- Colfax (16 km)
- Dobbins 1 S (21 km)
- Blue Canyon Airport (32 km)
- Auburn (33 km)
- Georgetown Ranger Station (38 km)
- Lake Spaulding (39 km)
- Strawberry Valley (40 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.