Frost dates for El Capitan Dam, CA
At El Capitan Dam, the median last spring frost (32°F) is Mar 19 and the median first fall frost is Dec 8, for a typical growing season of 270 days. For a 90% chance that the last frost has passed, wait until Jun 1. Nearby ZIP codes are in USDA hardiness zone 10a.
- Mar 19Last spring frost (median)50% chance of 32°F after this date
- Jun 1Safer planting date10% chance of 32°F after this date
- Dec 8First fall frost (median)50% chance of 32°F by this date
- 270 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 23 | Apr 24 | Jun 29 |
| 32°F | Dec 31 | Mar 19 | Jun 1 |
| 28°F | Dec 20 | Feb 22 | Apr 20 |
| 24°F | Dec 27 | Feb 4 | Mar 28 |
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 16 | Nov 19 | Dec 13 |
| 32°F | Oct 25 | Dec 8 | Jan 15 |
| 28°F | Nov 26 | Jan 1 | Feb 25 |
| 24°F | Dec 6 | Jan 18 | Mar 1 |
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 | 124 days | 198 days | 274 days |
| 32°F | 184 days | 270 days | 343 days |
| 28°F | 246 days | 333 days | 365 days |
| 24°F | 309 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 97% |
| 28°F | 72% |
| 24°F | 37% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 92040 | 10a | 30 to 35°F | 8 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 USC00042709, at 32.8856, -116.8150, elevation 183 m (600 ft).
- Data quality: Representative (10+ years), 16 years of freeze data.
- Average days per year at or below 32°F: 22.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Alpine (7 km)
- El Cajon (14 km)
- Ramona Fire Dept (16 km)
- Ramona Airport (19 km)
- Cuyamaca (24 km)
- San Pasqual Animal Pk (29 km)
- Rancho Bernardo (29 km)
- Julian Cdf (30 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.