Frost dates for 58207Grand Forks, ND
The average last spring frost in Grand Forks is May 10 and the average first fall frost is October 1, giving a typical growing season of about 144 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 10
- Average first fall frost
- Oct 1
- Growing season
- 144 days
Safer after May 24 (1-in-10 risk)
Possible by Sep 20 (1-in-10 risk)
Last frost typically in 196 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | May 7 · May 19 · Jun 1 | Sep 10 · Sep 23 · Oct 3 | 125 days | 100% |
| Frost / freeze (32°F) | Apr 28 · May 10 · May 24 | Sep 20 · Oct 1 · Oct 15 | 144 days | 100% |
| Hard freeze (28°F) | Apr 16 · Apr 30 · May 14 | Sep 29 · Oct 12 · Oct 25 | 163 days | 100% |
Planting calendar for Grand Forks
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 9 – Jun 15 |
| Tomatoes | Transplant outdoors | May 26 – Jun 11 |
| Peppers | Start seeds indoors | Apr 9 – May 10 |
| Peppers | Transplant outdoors | Jun 9 – Jul 10 |
| Eggplant | Start seeds indoors | Apr 26 – May 25 |
| Eggplant | Transplant outdoors | Jun 9 – Jul 10 |
| Cucumbers | Sow outdoors | Jun 9 – Jun 21 |
| Summer squash | Sow outdoors | May 26 – Jul 10 |
| Winter squash & pumpkins | Sow outdoors | Jun 9 – Jul 10 |
| Snap beans | Sow outdoors | May 26 – Jul 14 |
| Sweet corn | Sow outdoors | May 26 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 9 – Jul 10 |
| Okra | Sow outdoors | Jun 2 – Jun 25 |
| Peas | Sow outdoors (spring) | Apr 9 – May 25 |
| Potatoes | Plant outdoors (spring) | Apr 9 – Jun 9 |
| Onions | Start seeds indoors (spring) | Feb 26 – Mar 25 |
| Onions | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (spring) | Mar 22 – Apr 25 |
| Broccoli | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 12 – Apr 9 |
| Cabbage | Transplant outdoors (spring) | Apr 9 – May 10 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 9 – Jun 25 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Apr 2 – May 16 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 9 – May 30 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | Apr 26 – May 16 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 10 – Jun 25 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 58207 is matched to the NOAA station Grand Forks Univ (Nws), ND, 4.8 km away, at 830 ft elevation (0 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Grand Forks Univ (Nws), ND (used) | 830 ft | May 10 | Oct 1 |
| Grand Forks Intl Ap, ND | 842 ft | May 16 | Sep 27 |
| Crookston Nw Exp Stn, MN | 891 ft | May 11 | Sep 27 |
| Warren Wsd, MN | 855 ft | May 5 | Oct 2 |
Frost dates near Grand Forks
- Grand Forks, ND 58206 · last May 10, first Oct 1
- East Grand Forks, MN 56721 · last May 10, first Oct 1
- Emerado, ND 58228 · last May 16, first Sep 27
- Thompson, ND 58278 · last May 10, first Oct 1
- Manvel, ND 58256 · last May 16, first Sep 27
- Fisher, MN 56723 · last May 11, first Sep 27
- Grand Forks Afb, ND 58204 · last May 16, first Sep 27
- Reynolds, ND 58275 · last May 13, first Sep 27
Frequently asked questions
- When is the last frost in Grand Forks, ND?
- For ZIP code 58207, the average last spring frost (32°F) is May 10, based on NOAA 1991-2020 climate normals for the Grand Forks Univ (Nws), ND weather station. There is a 1-in-10 chance of a frost after May 24.
- When is the first frost in Grand Forks, ND?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 20, so tender plants are at risk from that point on.
- How long is the growing season in 58207?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 144 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.