Frost dates for San Antonio/seaworld, TX
At San Antonio/seaworld, the median last spring frost (32°F) is Feb 18 and the median first fall frost is Dec 9, for a typical growing season of 296 days. For a 90% chance that the last frost has passed, wait until Mar 16. Nearby ZIP codes are in USDA hardiness zones 8b to 9a.
- Feb 18Last spring frost (median)50% chance of 32°F after this date
- Mar 16Safer planting date10% chance of 32°F after this date
- Dec 9First fall frost (median)50% chance of 32°F by this date
- 296 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 11 | Mar 4 | Mar 31 |
| 32°F | Jan 18 | Feb 18 | Mar 16 |
| 28°F | Dec 17 | Jan 31 | Mar 3 |
| 24°F | Dec 8 | Jan 19 | Feb 22 |
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 5 | Nov 25 | Dec 15 |
| 32°F | Nov 17 | Dec 9 | Jan 13 |
| 28°F | Nov 28 | Dec 29 | Feb 9 |
| 24°F | Dec 4 | Jan 3 | Feb 12 |
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 | 233 days | 264 days | 297 days |
| 32°F | 260 days | 296 days | 334 days |
| 28°F | 291 days | 334 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 | 99% |
| 28°F | 79% |
| 24°F | 38% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 78251 | 9a | 20 to 25°F | 3 km |
| 78250 | 9a | 20 to 25°F | 7 km |
| 78245 | 9a | 20 to 25°F | 7 km |
| 78253 | 9a | 20 to 25°F | 8 km |
| 78238 | 9a | 20 to 25°F | 9 km |
| 78254 | 9a | 20 to 25°F | 9 km |
| 78066 | 9a | 20 to 25°F | 19 km |
| 78023 | 8b | 15 to 20°F | 20 km |
| 78056 | 9a | 20 to 25°F | 25 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 USC00418169, at 29.4508, -98.7028, elevation 286 m (940 ft).
- Data quality: Representative (10+ years), 14 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
- San Antonio Kelly AFB (14 km)
- San Antonio Incarnate Word (22 km)
- San Antonio Intl Airport (24 km)
- San Antonio Stinson Airport (26 km)
- Lytle 3w (28 km)
- Boerne (39 km)
- Randolph AFB (43 km)
- Hondo (44 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.