Frost dates for Thorsby Exp. Station, AL
At Thorsby Exp. Station, the median last spring frost (32°F) is Mar 21 and the median first fall frost is Nov 11, for a typical growing season of 235 days. For a 90% chance that the last frost has passed, wait until Apr 10. Nearby ZIP codes are in USDA hardiness zones 8a to 8b.
- Mar 21Last spring frost (median)50% chance of 32°F after this date
- Apr 10Safer planting date10% chance of 32°F after this date
- Nov 11First fall frost (median)50% chance of 32°F by this date
- 235 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 17 | Apr 5 | Apr 23 |
| 32°F | Feb 28 | Mar 21 | Apr 10 |
| 28°F | Feb 15 | Mar 7 | Mar 26 |
| 24°F | Jan 28 | Feb 22 | Mar 16 |
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 15 |
| 32°F | Oct 29 | Nov 11 | Dec 1 |
| 28°F | Nov 5 | Nov 25 | Dec 21 |
| 24°F | Nov 17 | Dec 10 | Jan 10 |
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 | 188 days | 210 days | 236 days |
| 32°F | 209 days | 235 days | 263 days |
| 28°F | 234 days | 262 days | 295 days |
| 24°F | 260 days | 293 days | 329 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 |
|---|---|---|---|
| 35085 | 8b | 15 to 20°F | 9 km |
| 35171 | 8a | 10 to 15°F | 9 km |
| 35143 | 8a | 10 to 15°F | 22 km |
| 36750 | 8b | 15 to 20°F | 22 km |
| 36792 | 8a | 10 to 15°F | 23 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 USC00018209, at 32.9206, -86.6708, elevation 207 m (680 ft).
- Data quality: Standard (24+ years of data), 24 years of freeze data.
- Average days per year at or below 32°F: 46.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Clanton 2 NE (9 km)
- Clanton (13 km)
- Alabaster Shelby Co Airport (30 km)
- Helena (42 km)
- Rockford 3 ESE (47 km)
- Childersburg Water Plant (51 km)
- Sylacauga 4 NE (53 km)
- Centreville 6 SW (53 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.