Frost dates by state › North Dakota
North Dakota frost dates
Average last spring and first fall frost dates for North Dakota’s largest cities, with each city’s USDA hardiness zone.
Reviewed October 2026
Among North Dakota’s 20 largest cities, the average last spring frost ranges from May 4 in Fargo to May 21 in Williston. Elevation, distance from the coast and city heat all shift the date, so use your own ZIP code below for the closest match.
| City | Average last spring frost | Average first fall frost | Frost-free days | Hardiness zone | Weather station used |
|---|---|---|---|---|---|
| Fargo | May 4 | Oct 2 | 151 | 4a | Fargo 3S, ND, 3 mi |
| Bismarck | May 10 | Sep 30 | 143 | 4a | Bismarck 2.4 Nnw, ND, 2 mi |
| Grand Forks | May 10 | Oct 1 | 144 | 4a | Grand Forks Univ (Nws), ND |
| Minot | May 10 | Oct 1 | 144 | 4a | Minot Intl Airport, ND |
| West Fargo | May 4 | Oct 2 | 151 | 4a | Fargo 3S, ND, 5 mi |
| Williston | May 21 | Sep 21 | 123 | 4a | Williston Sloulin Intl Airport, ND |
| Dickinson | May 20 | Sep 22 | 125 | 4b | Dickinson, ND |
| Mandan | May 13 | Sep 27 | 137 | 4a | Mandan Exp Stn, ND, 2 mi |
| Jamestown | May 8 | Sep 29 | 144 | 4a–4b | Jamestown State Hosp, ND, 2 mi |
| Wahpeton | May 4 | Oct 3 | 152 | 4a | Breckenridge 3E, MN, 5 mi |
| Devils Lake | May 6 | Oct 5 | 152 | 4a | Devils Lake Kdlr, ND |
| Valley City | May 13 | Sep 26 | 136 | 4a | Valley City 3 Nnw, ND, 2 mi |
| Horace | May 4 | Oct 2 | 151 | 4a | Fargo 3S, ND, 7 mi |
| Watford City | May 9 | Sep 27 | 141 | 4a | Watford City, ND |
| Lincoln | May 14 | Sep 30 | 139 | 4a | Bismarck Wfo, ND, 3 mi |
| Grafton | May 4 | Oct 7 | 156 | 4a | Grafton, ND |
| Beulah | May 21 | Sep 20 | 122 | 4a | Beulah 1 W, ND |
| New Town | May 20 | Sep 20 | 123 | 4a | Keene 3S, ND, 21 mi |
| Casselton | May 9 | Oct 1 | 145 | 4a | Casselton Agronomy Farm, ND, 2 mi |
| Rugby | May 17 | Sep 23 | 129 | 3b | Rugby, ND |
Frost dates are the dates after (spring) or before (fall) which the chance of a 32°F freeze is below 50%, from NOAA’s 1991–2020 U.S. Climate Normals for the weather station nearest each city’s center. Zones are from the 2023 USDA Plant Hardiness Zone Map for the ZIP codes around each city; a range means nearby ZIP codes differ. Cities are the 20 largest by Census Bureau 2024 population estimates.
An average is not a guarantee. There’s still about a 1 in 2 chance of frost after the average last spring date. Many gardeners wait an extra week or two before setting out tomatoes, peppers and basil, and keep covers handy.
Planting dates for Fargo
Timed from Fargo’s average last frost of May 4, using University of New Hampshire Extension’s planting guidance. For your exact dates, enter your ZIP code in the calendar below.
| Crop | Start seeds indoors | Plant outside |
|---|---|---|
| Tomatoes | Mar 16 to Mar 30 | May 11 to May 18 |
| Peppers | Mar 9 to Mar 23 | May 18 |
| Lettuce | Mar 2 to Mar 9 | Apr 6 to Apr 13 |
| Broccoli | Feb 23 to Mar 9 | Apr 6 to Apr 20 |
| Cucumbers | Apr 13 to Apr 20 | May 11 to May 18 |
| Basil | Mar 23 to Apr 6 | May 18 |
When to plant, for your garden
Your seed-starting and planting dates, timed from your last spring frost. Full calendar, 12 crops.
Enter your ZIP code to look up your average last frost date and hardiness zone, or type the date in yourself.
Frost dates: NOAA U.S. Climate Normals, 1991–2020. Hardiness zones: USDA Plant Hardiness Zone Map, 2023, ZIP code data from PRISM Group, Oregon State University, prism.oregonstate.edu, accessed Oct. 20, 2026.
More about frost dates
How to find your last frost date, and what your zone means · Full planting calendar · How to start seeds indoors
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