Frost dates for Duncan, OK
At Duncan, the median last spring frost (32°F) is Mar 25 and the median first fall frost is Nov 7, for a typical growing season of 225 days. For a 90% chance that the last frost has passed, wait until Apr 12. Nearby ZIP codes are in USDA hardiness zones 7b to 8a.
- Mar 25Last spring frost (median)50% chance of 32°F after this date
- Apr 12Safer planting date10% chance of 32°F after this date
- Nov 7First fall frost (median)50% chance of 32°F by this date
- 225 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 21 | Apr 7 | Apr 24 |
| 32°F | Mar 3 | Mar 25 | Apr 12 |
| 28°F | Feb 24 | Mar 11 | Mar 31 |
| 24°F | Feb 10 | Mar 1 | Mar 19 |
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 16 | Oct 30 | Nov 13 |
| 32°F | Oct 22 | Nov 7 | Nov 23 |
| 28°F | Oct 31 | Nov 16 | Dec 4 |
| 24°F | Nov 7 | Nov 28 | Dec 18 |
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 | 183 days | 205 days | 227 days |
| 32°F | 200 days | 225 days | 251 days |
| 28°F | 223 days | 249 days | 272 days |
| 24°F | 245 days | 270 days | 299 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 |
|---|---|---|---|
| 73533 | 8a | 10 to 15°F | 8 km |
| 73055 | 7b | 5 to 10°F | 16 km |
| 73529 | 8a | 10 to 15°F | 18 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 USC00342660, at 34.5011, -97.9592, elevation 343 m (1,125 ft).
- Data quality: Representative (10+ years), 21 years of freeze data.
- Average days per year at or below 32°F: 69.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Velma 7nw Mesonet (18 km)
- Acme Mesonet (35 km)
- Walters (35 km)
- Waurika (36 km)
- Waurika 1ene Mesonet (37 km)
- Walters 4nw Mesonet (37 km)
- Lawton Muni Airport (42 km)
- Lindsay 2 W (47 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.