Frost dates for Hebron, ND
At Hebron, the median last spring frost (32°F) is May 19 and the median first fall frost is Sep 21, for a typical growing season of 123 days. For a 90% chance that the last frost has passed, wait until Jun 2. Nearby ZIP codes are in USDA hardiness zone 4a.
- May 19Last spring frost (median)50% chance of 32°F after this date
- Jun 2Safer planting date10% chance of 32°F after this date
- Sep 21First fall frost (median)50% chance of 32°F by this date
- 123 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 17 | May 31 | Jun 14 |
| 32°F | May 7 | May 19 | Jun 2 |
| 28°F | Apr 30 | May 10 | May 23 |
| 24°F | Apr 17 | May 2 | May 15 |
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 25 | Sep 10 | Sep 24 |
| 32°F | Sep 7 | Sep 21 | Oct 4 |
| 28°F | Sep 15 | Sep 30 | Oct 14 |
| 24°F | Sep 24 | Oct 9 | Oct 22 |
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 | 80 days | 100 days | 120 days |
| 32°F | 104 days | 123 days | 141 days |
| 28°F | 122 days | 141 days | 160 days |
| 24°F | 140 days | 160 days | 178 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 |
|---|---|---|---|
| 58638 | 4a | -30 to -25°F | 1 km |
| 58631 | 4a | -30 to -25°F | 20 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 USC00324102, at 46.9075, -102.0383, elevation 658 m (2,160 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 194.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Richardton Abbey (21 km)
- Taylor 7 NNW (35 km)
- Heart Butte Dam (39 km)
- New Salem 5nw (42 km)
- Beulah 1 W (44 km)
- Almont (45 km)
- Dickinson (56 km)
- Theodore Roosevelt Airport (59 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.