Frost dates for Mullen 21 NW, NE
At Mullen 21 NW, the median last spring frost (32°F) is May 10 and the median first fall frost is Oct 1, for a typical growing season of 142 days. For a 90% chance that the last frost has passed, wait until May 24. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- May 10Last spring frost (median)50% chance of 32°F after this date
- May 24Safer planting date10% chance of 32°F after this date
- Oct 1First fall frost (median)50% chance of 32°F by this date
- 142 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 | May 9 | May 22 | Jun 5 |
| 32°F | Apr 29 | May 10 | May 24 |
| 28°F | Apr 16 | May 1 | May 16 |
| 24°F | Apr 5 | Apr 20 | May 4 |
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 | Sep 10 | Sep 24 | Oct 4 |
| 32°F | Sep 17 | Oct 1 | Oct 11 |
| 28°F | Sep 26 | Oct 9 | Oct 20 |
| 24°F | Oct 2 | Oct 17 | Oct 29 |
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 | 105 days | 123 days | 140 days |
| 32°F | 123 days | 142 days | 157 days |
| 28°F | 138 days | 159 days | 178 days |
| 24°F | 159 days | 179 days | 199 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 69152 | 5b | -15 to -10°F | 26 km |
| 69366 | 5b | -15 to -10°F | 29 km |
| 69161 | 5b | -15 to -10°F | 47 km |
| 69350 | 5a | -20 to -15°F | 48 km |
| 69333 | 5a | -20 to -15°F | 56 km |
| 69219 | 5a | -20 to -15°F | 57 km |
| 69218 | 5a | -20 to -15°F | 63 km |
| 69166 | 5b | -15 to -10°F | 64 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 USC00255702, at 42.2506, -101.3364, elevation 1055 m (3,460 ft).
- Data quality: Representative (10+ years), 14 years of freeze data.
- Average days per year at or below 32°F: 177.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Whitman 5 ENE (22 km)
- Mullen (33 km)
- Valentine Nwr (64 km)
- Ellsworth 15 NNE (72 km)
- Merriman (80 km)
- Arthur (81 km)
- Ellsworth 2w (84 km)
- Kilgore 1ne (84 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.