Frost dates for Mertzon 12nnw, TX
At Mertzon 12nnw, the median last spring frost (32°F) is Apr 1 and the median first fall frost is Nov 4, for a typical growing season of 215 days. For a 90% chance that the last frost has passed, wait until Apr 19. Nearby ZIP codes are in USDA hardiness zone 8a.
- Apr 1Last spring frost (median)50% chance of 32°F after this date
- Apr 19Safer planting date10% chance of 32°F after this date
- Nov 4First fall frost (median)50% chance of 32°F by this date
- 215 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 28 | Apr 12 | Apr 29 |
| 32°F | Mar 14 | Apr 1 | Apr 19 |
| 28°F | Mar 2 | Mar 19 | Apr 7 |
| 24°F | Feb 15 | Mar 8 | 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 | Oct 12 | Oct 26 | Nov 7 |
| 32°F | Oct 21 | Nov 4 | Nov 18 |
| 28°F | Oct 29 | Nov 12 | Nov 30 |
| 24°F | Nov 7 | Nov 25 | Dec 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 | 174 days | 194 days | 216 days |
| 32°F | 193 days | 215 days | 240 days |
| 28°F | 215 days | 237 days | 264 days |
| 24°F | 236 days | 261 days | 288 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 76941 | 8a | 10 to 15°F | 21 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 USC00415861, at 31.4364, -100.8781, elevation 672 m (2,205 ft).
- Data quality: Estimated from nearby stations (2+ years), 8 years of freeze data.
- Average days per year at or below 32°F: 74.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Water Valley (30 km)
- San Angelo WFO (37 km)
- San Angelo (37 km)
- Cope Rch (40 km)
- Sterling City (45 km)
- Robert Lee 4wsw (59 km)
- Big Lake 2 (61 km)
- Eldorado (68 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.