Frost dates for Twitchell Dam, CA
At Twitchell Dam, the median last spring frost (32°F) is Feb 4 and the median first fall frost is Dec 4, for a typical growing season of 301 days. For a 90% chance that the last frost has passed, wait until Mar 31. Nearby ZIP codes are in USDA hardiness zones 8b to 9b.
- Feb 4Last spring frost (median)50% chance of 32°F after this date
- Mar 31Safer planting date10% chance of 32°F after this date
- Dec 4First fall frost (median)50% chance of 32°F by this date
- 301 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 | Feb 14 | Mar 31 | Apr 26 |
| 32°F | Dec 27 | Feb 4 | Mar 31 |
| 28°F | Dec 4 | Dec 31 | Feb 3 |
| 24°F | Dec 10 | Dec 28 | Jan 10 |
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 21 | Nov 16 | Dec 6 |
| 32°F | Nov 14 | Dec 4 | Dec 28 |
| 28°F | Nov 26 | Dec 17 | Jan 14 |
| 24°F | Dec 7 | Dec 25 | Jan 9 |
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 | 194 days | 231 days | 278 days |
| 32°F | 244 days | 301 days | 343 days |
| 28°F | 321 days | 353 days | 365 days |
| 24°F | 358 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 98% |
| 28°F | 66% |
| 24°F | 13% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 93454 | 9b | 25 to 30°F | 9 km |
| 93453 | 8b | 15 to 20°F | 30 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 USC00049111, at 34.9881, -120.3211, elevation 177 m (582 ft).
- Data quality: Representative (10+ years), 15 years of freeze data.
- Average days per year at or below 32°F: 14.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Santa Maria Public Airport (15 km)
- Pismo Beach (38 km)
- Lompoc (39 km)
- San Luis Obispo Airport (40 km)
- San Luis Obispo Poly (47 km)
- Cachuma Lake (55 km)
- New Cuyama Fire Station (58 km)
- Morro Bay Fire Dept (64 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.