Frost dates for Santa Rosa, CA
At Santa Rosa, the median last spring frost (32°F) is Feb 25 and the median first fall frost is Dec 1, for a typical growing season of 279 days. For a 90% chance that the last frost has passed, wait until Mar 29. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Feb 25Last spring frost (median)50% chance of 32°F after this date
- Mar 29Safer planting date10% chance of 32°F after this date
- Dec 1First fall frost (median)50% chance of 32°F by this date
- 279 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 6 | Apr 3 | Apr 25 |
| 32°F | Jan 21 | Feb 25 | Mar 29 |
| 28°F | Dec 22 | Jan 20 | Feb 24 |
| 24°F | Dec 10 | Jan 2 | Jan 31 |
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 31 | Nov 14 | Dec 1 |
| 32°F | Nov 10 | Dec 1 | Dec 24 |
| 28°F | Nov 26 | Dec 16 | Jan 19 |
| 24°F | Dec 3 | Dec 29 | Jan 22 |
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 | 193 days | 223 days | 256 days |
| 32°F | 244 days | 279 days | 319 days |
| 28°F | 295 days | 335 days | 365 days |
| 24°F | 345 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 99% |
| 28°F | 83% |
| 24°F | 30% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 95405 | 9a | 20 to 25°F | 4 km |
| 95407 | 9a | 20 to 25°F | 7 km |
| 95404 | 9b | 25 to 30°F | 8 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 USC00047965, at 38.4558, -122.7133, elevation 51 m (166 ft).
- Data quality: Representative (10+ years), 22 years of freeze data.
- Average days per year at or below 32°F: 15.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Santa Rosa Sonoma Co Airport (10 km)
- Graton (13 km)
- Calistoga (18 km)
- Saint Helena (22 km)
- Occidental (23 km)
- Healdsburg (23 km)
- Petaluma Airport (24 km)
- Angwin Pacific Union College (27 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.