Frost dates for Vallejo, CA
At Vallejo, the median last spring frost (32°F) is Jan 17 and the median first fall frost is Dec 27, for a typical growing season of 346 days. For a 90% chance that the last frost has passed, wait until Mar 4. Nearby ZIP codes are in USDA hardiness zone 9b.
- Jan 17Last spring frost (median)50% chance of 32°F after this date
- Mar 4Safer planting date10% chance of 32°F after this date
- Dec 27First fall frost (median)50% chance of 32°F by this date
- 346 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 | Jan 19 | Mar 4 | Apr 8 |
| 32°F | Dec 23 | Jan 17 | Mar 4 |
| 28°F | Dec 19 | Jan 5 | Jan 19 |
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 21 | Dec 7 | Jan 2 |
| 32°F | Dec 4 | Dec 27 | Feb 4 |
| 28°F | Dec 13 | Jan 2 | 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 | 241 days | 279 days | 328 days |
| 32°F | 291 days | 346 days | 365 days |
| 28°F | 354 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 | 75% |
| 28°F | 23% |
| 24°F | 4% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 94591 | 9b | 25 to 30°F | 3 km |
| 94590 | 9b | 25 to 30°F | 6 km |
| 94510 | 9b | 25 to 30°F | 6 km |
| 94569 | 9b | 25 to 30°F | 6 km |
| 94525 | 9b | 25 to 30°F | 7 km |
| 94589 | 9b | 25 to 30°F | 7 km |
| 94592 | 9b | 25 to 30°F | 9 km |
| 94572 | 9b | 25 to 30°F | 9 km |
| 94547 | 9b | 25 to 30°F | 12 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 USC00049219, at 38.1000, -122.1869, elevation 104 m (341 ft).
- Data quality: Estimated from nearby stations (2+ years), 7 years of freeze data.
- Average days per year at or below 32°F: 4.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Martinez Water Plant (12 km)
- Napa Co Airport (15 km)
- Concord Wastewater Plant (17 km)
- Concord Buchanan Field (17 km)
- Napa State Hospital (21 km)
- Fairfield (22 km)
- Berkeley (26 km)
- Richmond (26 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.