Frost dates for Calistoga, CA
At Calistoga, the median last spring frost (32°F) is Mar 2 and the median first fall frost is Nov 23, for a typical growing season of 263 days. For a 90% chance that the last frost has passed, wait until Apr 18. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Mar 2Last spring frost (median)50% chance of 32°F after this date
- Apr 18Safer planting date10% chance of 32°F after this date
- Nov 23First fall frost (median)50% chance of 32°F by this date
- 263 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 10 | Apr 13 | May 18 |
| 32°F | Jan 19 | Mar 2 | Apr 18 |
| 28°F | Dec 12 | Jan 23 | Mar 6 |
| 24°F | Dec 3 | Dec 31 | Feb 14 |
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 13 | Nov 4 | Nov 27 |
| 32°F | Nov 1 | Nov 23 | Dec 20 |
| 28°F | Nov 16 | Dec 6 | Jan 15 |
| 24°F | Nov 30 | Dec 19 | Jan 28 |
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 | 165 days | 203 days | 244 days |
| 32°F | 208 days | 263 days | 313 days |
| 28°F | 272 days | 327 days | 365 days |
| 24°F | 326 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 87% |
| 24°F | 42% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 94515 | 9b | 25 to 30°F | 5 km |
| 95461 | 9a | 20 to 25°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 USC00041312, at 38.5961, -122.6014, elevation 122 m (400 ft).
- Data quality: Representative (10+ years), 26 years of freeze data.
- Average days per year at or below 32°F: 36.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Angwin Pacific Union College (14 km)
- Saint Helena (15 km)
- Santa Rosa (18 km)
- Santa Rosa Sonoma Co Airport (21 km)
- Healdsburg (23 km)
- Graton (29 km)
- Sonoma (35 km)
- Clearlake 4 SE (37 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.