Frost dates for Ukiah, CA
At Ukiah, the median last spring frost (32°F) is Mar 19 and the median first fall frost is Nov 20, for a typical growing season of 245 days. For a 90% chance that the last frost has passed, wait until Apr 15. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Mar 19Last spring frost (median)50% chance of 32°F after this date
- Apr 15Safer planting date10% chance of 32°F after this date
- Nov 20First fall frost (median)50% chance of 32°F by this date
- 245 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 | Mar 31 | Apr 17 | May 9 |
| 32°F | Feb 13 | Mar 19 | Apr 15 |
| 28°F | Dec 25 | Feb 6 | Mar 13 |
| 24°F | Dec 11 | Jan 7 | Feb 24 |
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 18 | Nov 2 | Nov 19 |
| 32°F | Nov 2 | Nov 20 | Dec 9 |
| 28°F | Nov 17 | Dec 5 | Jan 6 |
| 24°F | Nov 30 | Dec 18 | Jan 26 |
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 | 172 days | 198 days | 224 days |
| 32°F | 212 days | 245 days | 285 days |
| 28°F | 267 days | 309 days | 351 days |
| 24°F | 321 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 94% |
| 24°F | 51% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 95482 | 9a | 20 to 25°F | 5 km |
| 95466 | 9b | 25 to 30°F | 27 km |
| 95463 | 9b | 25 to 30°F | 32 km |
| 95432 | 9b | 25 to 30°F | 38 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 USC00049122, at 39.1467, -123.2103, elevation 194 m (636 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 34.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Ukiah Muni Airport (2 km)
- Potter Valley Powerhouse (25 km)
- Willits 1 NE (32 km)
- Cloverdale (42 km)
- Clearlake 4 SE (61 km)
- Fort Bragg 5 N (62 km)
- East Park Rsvr (64 km)
- Healdsburg (65 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.