Frost dates for Potter Valley Powerhouse, CA
At Potter Valley Powerhouse, the median last spring frost (32°F) is Apr 8 and the median first fall frost is Nov 6, for a typical growing season of 211 days. For a 90% chance that the last frost has passed, wait until Apr 29. Nearby ZIP codes are in USDA hardiness zones 8b to 9a.
- Apr 8Last spring frost (median)50% chance of 32°F after this date
- Apr 29Safer planting date10% chance of 32°F after this date
- Nov 6First fall frost (median)50% chance of 32°F by this date
- 211 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 15 | May 2 | May 25 |
| 32°F | Mar 11 | Apr 8 | Apr 29 |
| 28°F | Jan 25 | Feb 28 | Apr 2 |
| 24°F | Dec 17 | Jan 26 | Feb 28 |
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 2 | Oct 21 | Nov 6 |
| 32°F | Oct 20 | Nov 6 | Nov 24 |
| 28°F | Nov 3 | Nov 22 | Dec 12 |
| 24°F | Nov 17 | Dec 7 | Jan 5 |
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 | 141 days | 171 days | 193 days |
| 32°F | 184 days | 211 days | 243 days |
| 28°F | 231 days | 268 days | 307 days |
| 24°F | 278 days | 321 days | 359 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 90% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 95469 | 9a | 20 to 25°F | 6 km |
| 95470 | 9a | 20 to 25°F | 12 km |
| 95493 | 8b | 15 to 20°F | 20 km |
| 95485 | 9a | 20 to 25°F | 24 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 USC00047109, at 39.3619, -123.1286, elevation 310 m (1,018 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 54.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Willits 1 NE (19 km)
- Ukiah (25 km)
- Ukiah Muni Airport (27 km)
- Covelo (51 km)
- East Park Rsvr (53 km)
- Fort Bragg 5 N (56 km)
- Stony Gorge Rsvr (57 km)
- Cloverdale (64 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.