Frost dates for Hillsboro 3 N, ND
At Hillsboro 3 N, the median last spring frost (32°F) is May 2 and the median first fall frost is Oct 9, for a typical growing season of 158 days. For a 90% chance that the last frost has passed, wait until May 17. Nearby ZIP codes are in USDA hardiness zone 4a.
- May 2Last spring frost (median)50% chance of 32°F after this date
- May 17Safer planting date10% chance of 32°F after this date
- Oct 9First fall frost (median)50% chance of 32°F by this date
- 158 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 | Apr 29 | May 11 | May 24 |
| 32°F | Apr 15 | May 2 | May 17 |
| 28°F | Apr 6 | Apr 23 | May 8 |
| 24°F | Mar 31 | Apr 11 | Apr 29 |
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 15 | Sep 30 | Oct 13 |
| 32°F | Sep 25 | Oct 9 | Oct 25 |
| 28°F | Oct 2 | Oct 20 | Nov 4 |
| 24°F | Oct 12 | Oct 30 | Nov 11 |
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 | 122 days | 140 days | 157 days |
| 32°F | 139 days | 158 days | 179 days |
| 28°F | 155 days | 177 days | 201 days |
| 24°F | 176 days | 197 days | 218 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 |
|---|---|---|---|
| 58045 | 4a | -30 to -25°F | 7 km |
| 58223 | 4a | -30 to -25°F | 10 km |
| 58219 | 4a | -30 to -25°F | 15 km |
| 58218 | 4a | -30 to -25°F | 17 km |
| 58009 | 4a | -30 to -25°F | 18 km |
| 58038 | 4a | -30 to -25°F | 22 km |
| 56581 | 4a | -30 to -25°F | 23 km |
| 56568 | 4a | -30 to -25°F | 24 km |
| 58048 | 4a | -30 to -25°F | 29 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 USC00324203, at 47.4389, -97.0664, elevation 277 m (910 ft).
- Data quality: Representative (10+ years), 21 years of freeze data.
- Average days per year at or below 32°F: 174.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Mayville (22 km)
- Colgate (49 km)
- Grand Forks Univ (nws) (54 km)
- Grand Forks Intl Airport (57 km)
- Fargo Hector Intl Airport (60 km)
- Casselton Agronomy Farm (64 km)
- Larimore 4sw (68 km)
- Fargo 3s (71 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.