Frost dates for Clearlake 4 SE, CA
At Clearlake 4 SE, the median last spring frost (32°F) is Apr 10 and the median first fall frost is Nov 6, for a typical growing season of 209 days. For a 90% chance that the last frost has passed, wait until Apr 30. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Apr 10Last spring frost (median)50% chance of 32°F after this date
- Apr 30Safer planting date10% chance of 32°F after this date
- Nov 6First fall frost (median)50% chance of 32°F by this date
- 209 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 | Apr 14 | Apr 30 | May 16 |
| 32°F | Mar 24 | Apr 10 | Apr 30 |
| 28°F | Feb 12 | Mar 14 | Apr 7 |
| 24°F | Dec 29 | Feb 7 | Mar 8 |
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 11 | Oct 27 | Nov 7 |
| 32°F | Oct 24 | Nov 6 | Nov 20 |
| 28°F | Nov 4 | Nov 21 | Dec 8 |
| 24°F | Nov 17 | Dec 6 | Jan 11 |
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 | 155 days | 178 days | 196 days |
| 32°F | 186 days | 209 days | 231 days |
| 28°F | 222 days | 250 days | 291 days |
| 24°F | 269 days | 309 days | 348 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 96% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 95457 | 9a | 20 to 25°F | 2 km |
| 95422 | 9a | 20 to 25°F | 9 km |
| 95467 | 9a | 20 to 25°F | 12 km |
| 95423 | 9a | 20 to 25°F | 17 km |
| 95426 | 9b | 25 to 30°F | 18 km |
| 95451 | 9b | 25 to 30°F | 19 km |
| 95443 | 9b | 25 to 30°F | 20 km |
| 95679 | 9b | 25 to 30°F | 24 km |
| 95637 | 9b | 25 to 30°F | 27 km |
| 95458 | 9a | 20 to 25°F | 27 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 USC00041806, at 38.9239, -122.5672, elevation 411 m (1,349 ft).
- Data quality: Representative (10+ years), 12 years of freeze data.
- Average days per year at or below 32°F: 72.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Calistoga (37 km)
- Angwin Pacific Union College (41 km)
- Healdsburg (42 km)
- Cloverdale (42 km)
- Saint Helena (47 km)
- East Park Rsvr (49 km)
- Santa Rosa Sonoma Co Airport (51 km)
- Santa Rosa (54 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.