Frost dates for Hettinger Exp. Station, ND
At Hettinger Exp. Station, the median last spring frost (32°F) is May 21 and the median first fall frost is Sep 21, for a typical growing season of 120 days. For a 90% chance that the last frost has passed, wait until Jun 5. Nearby ZIP codes are in USDA hardiness zones 4a to 4b.
- May 21Last spring frost (median)50% chance of 32°F after this date
- Jun 5Safer planting date10% chance of 32°F after this date
- Sep 21First fall frost (median)50% chance of 32°F by this date
- 120 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 20 | Jun 2 | Jun 22 |
| 32°F | May 10 | May 21 | Jun 5 |
| 28°F | May 1 | May 11 | May 25 |
| 24°F | Apr 16 | May 2 | May 14 |
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 | Aug 23 | Sep 9 | Sep 23 |
| 32°F | Sep 5 | Sep 21 | Oct 2 |
| 28°F | Sep 16 | Sep 29 | Oct 10 |
| 24°F | Sep 23 | Oct 6 | Oct 19 |
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 | 70 days | 97 days | 117 days |
| 32°F | 97 days | 120 days | 137 days |
| 28°F | 120 days | 140 days | 156 days |
| 24°F | 139 days | 158 days | 177 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 |
|---|---|---|---|
| 58639 | 4b | -25 to -20°F | 7 km |
| 58649 | 4b | -25 to -20°F | 25 km |
| 57640 | 4b | -25 to -20°F | 27 km |
| 57638 | 4b | -25 to -20°F | 35 km |
| 57650 | 4b | -25 to -20°F | 36 km |
| 58653 | 4b | -25 to -20°F | 38 km |
| 58650 | 4a | -30 to -25°F | 48 km |
| 58646 | 4a | -30 to -25°F | 51 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 USC00324180, at 46.0044, -102.6472, elevation 824 m (2,703 ft).
- Data quality: Representative (10+ years), 17 years of freeze data.
- Average days per year at or below 32°F: 202.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Hettinger Muni Airport (1 km)
- Mott (48 km)
- Bowman (60 km)
- New England (62 km)
- Pretty Rock (64 km)
- Amidon (74 km)
- Theodore Roosevelt Airport (89 km)
- Heart Butte Dam (92 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.