Frost dates for Occidental, CA
At Occidental, the median last spring frost (32°F) is Jan 29 and the median first fall frost is Dec 30, for a typical growing season of 347 days. For a 90% chance that the last frost has passed, wait until Mar 17. Nearby ZIP codes are in USDA hardiness zones 9b to 10a.
- Jan 29Last spring frost (median)50% chance of 32°F after this date
- Mar 17Safer planting date10% chance of 32°F after this date
- Dec 30First fall frost (median)50% chance of 32°F by this date
- 347 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 | Feb 3 | Mar 24 | Apr 24 |
| 32°F | Dec 17 | Jan 29 | Mar 17 |
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 | Nov 20 | Dec 8 | Jan 9 |
| 32°F | Dec 1 | Dec 30 | Feb 27 |
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 | 221 days | 258 days | 308 days |
| 32°F | 290 days | 347 days | 365 days |
| 28°F | 365 days | 365 days | 365 days |
| 24°F | 365 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 67% |
| 28°F | 10% |
| 24°F | 0% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 94922 | 9b | 25 to 30°F | 3 km |
| 95419 | 9b | 25 to 30°F | 4 km |
| 94972 | 9b | 25 to 30°F | 6 km |
| 95465 | 10a | 30 to 35°F | 8 km |
| 95462 | 9b | 25 to 30°F | 11 km |
| 95430 | 9b | 25 to 30°F | 11 km |
| 95486 | 9b | 25 to 30°F | 11 km |
| 95446 | 9b | 25 to 30°F | 15 km |
| 94971 | 9b | 25 to 30°F | 18 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 USC00046370, at 38.3858, -122.9661, elevation 264 m (865 ft).
- Data quality: Estimated from nearby stations (2+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 3.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Graton (10 km)
- Bodega 6 WSW (12 km)
- Santa Rosa Sonoma Co Airport (19 km)
- Santa Rosa (23 km)
- Fort Ross (28 km)
- Healdsburg (28 km)
- Petaluma Airport (34 km)
- Calistoga (39 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.