Frost dates for Somerville Dam, TX
At Somerville Dam, the median last spring frost (32°F) is Mar 18 and the median first fall frost is Nov 9, for a typical growing season of 238 days. For a 90% chance that the last frost has passed, wait until Apr 6. Nearby ZIP codes are in USDA hardiness zone 9a.
- Mar 18Last spring frost (median)50% chance of 32°F after this date
- Apr 6Safer planting date10% chance of 32°F after this date
- Nov 9First fall frost (median)50% chance of 32°F by this date
- 238 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 | Mar 12 | Apr 1 | Apr 20 |
| 32°F | Feb 25 | Mar 18 | Apr 6 |
| 28°F | Feb 4 | Mar 5 | Mar 24 |
| 24°F | Jan 17 | Feb 16 | Mar 13 |
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 19 | Nov 1 | Nov 17 |
| 32°F | Oct 26 | Nov 9 | Nov 30 |
| 28°F | Nov 3 | Nov 23 | Dec 14 |
| 24°F | Nov 14 | Dec 7 | 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 | 192 days | 213 days | 239 days |
| 32°F | 211 days | 238 days | 267 days |
| 28°F | 234 days | 263 days | 298 days |
| 24°F | 257 days | 298 days | 339 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 99% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 77863 | 9a | 20 to 25°F | 6 km |
| 77879 | 9a | 20 to 25°F | 11 km |
| 77835 | 9a | 20 to 25°F | 17 km |
| 77852 | 9a | 20 to 25°F | 23 km |
| 78932 | 9a | 20 to 25°F | 26 km |
| 77836 | 9a | 20 to 25°F | 26 km |
| 78946 | 9a | 20 to 25°F | 28 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 USC00418446, at 30.3367, -96.5403, elevation 80 m (263 ft).
- Data quality: Representative (10+ years), 19 years of freeze data.
- Average days per year at or below 32°F: 37.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Brenham (24 km)
- College Station (33 km)
- Washington State Park (37 km)
- Bellville 6nne (46 km)
- Lexington (46 km)
- La Grange (57 km)
- Cameron (70 km)
- Smithville (70 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.