Frost dates for Graton, CA
At Graton, the median last spring frost (32°F) is Mar 20 and the median first fall frost is Nov 13, for a typical growing season of 240 days. For a 90% chance that the last frost has passed, wait until Apr 19. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Mar 20Last spring frost (median)50% chance of 32°F after this date
- Apr 19Safer planting date10% chance of 32°F after this date
- Nov 13First fall frost (median)50% chance of 32°F by this date
- 240 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 23 | May 16 |
| 32°F | Feb 12 | Mar 20 | Apr 19 |
| 28°F | Dec 25 | Feb 1 | Mar 7 |
| 24°F | Dec 6 | 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 | Sep 29 | Oct 24 | Nov 11 |
| 32°F | Oct 26 | Nov 13 | Dec 6 |
| 28°F | Nov 12 | Dec 3 | Jan 8 |
| 24°F | Nov 24 | Dec 17 | Jan 19 |
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 | 149 days | 182 days | 215 days |
| 32°F | 200 days | 240 days | 285 days |
| 28°F | 266 days | 307 days | 347 days |
| 24°F | 323 days | 357 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 95% |
| 24°F | 55% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 95444 | 9a | 20 to 25°F | 0 km |
| 95472 | 9a | 20 to 25°F | 4 km |
| 95436 | 9b | 25 to 30°F | 7 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 USC00043578, at 38.4306, -122.8647, elevation 61 m (200 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 43.
- 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 (9 km)
- Occidental (10 km)
- Santa Rosa (13 km)
- Bodega 6 WSW (22 km)
- Healdsburg (22 km)
- Calistoga (29 km)
- Petaluma Airport (30 km)
- Fort Ross (34 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.