Frost dates for 58205Grand Forks Afb, ND
The average last spring frost in Grand Forks Afb is May 16 and the average first fall frost is September 27, giving a typical growing season of about 133 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 16
- Average first fall frost
- Sep 27
- Growing season
- 133 days
Safer after May 31 (1-in-10 risk)
Possible by Sep 15 (1-in-10 risk)
Last frost typically in 202 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 13 · May 26 · Jun 7 | Sep 4 · Sep 18 · Sep 28 | 113 days | 100% |
| Frost / freeze (32°F) | May 3 · May 16 · May 31 | Sep 15 · Sep 27 · Oct 8 | 133 days | 100% |
| Hard freeze (28°F) | Apr 20 · May 4 · May 19 | Sep 23 · Oct 5 · Oct 19 | 152 days | 100% |
Planting calendar for Grand Forks Afb
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 15 – Jun 21 |
| Tomatoes | Transplant outdoors | Jun 1 – Jun 7 |
| Peppers | Start seeds indoors | Apr 15 – May 16 |
| Peppers | Transplant outdoors | Jun 15 – Jul 16 |
| Eggplant | Start seeds indoors | May 2 – May 31 |
| Eggplant | Transplant outdoors | Jun 15 – Jul 16 |
| Cucumbers | Sow outdoors | Jun 15 – Jun 17 |
| Summer squash | Sow outdoors | Jun 1 – Jul 16 |
| Winter squash & pumpkins | Sow outdoors | Jun 15 – Jul 16 |
| Snap beans | Sow outdoors | Jun 1 – Jul 10 |
| Sweet corn | Sow outdoors | Jun 1 – Jun 7 |
| Watermelon & cantaloupe | Sow outdoors | Jun 15 – Jul 16 |
| Okra | Sow outdoors | Jun 8 – Jul 1 |
| Peas | Sow outdoors (spring) | Apr 15 – May 31 |
| Potatoes | Plant outdoors (spring) | Apr 15 – Jun 15 |
| Onions | Start seeds indoors (spring) | Mar 4 – Mar 31 |
| Onions | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (spring) | Mar 28 – May 1 |
| Broccoli | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (fall) | May 28 – Jun 7 |
| Broccoli | Transplant outdoors (fall) | Jun 27 – Jul 8 |
| Cabbage | Start seeds indoors (spring) | Mar 18 – Apr 15 |
| Cabbage | Transplant outdoors (spring) | Apr 15 – May 16 |
| Cabbage | Start seeds indoors (fall) | May 18 – Jun 17 |
| Cabbage | Transplant outdoors (fall) | Jun 17 – Jul 18 |
| Leaf lettuce | Sow outdoors (spring) | Apr 15 – Jul 1 |
| Leaf lettuce | Sow outdoors (fall) | Jun 17 – Aug 3 |
| Spinach | Sow outdoors (spring) | Apr 8 – May 22 |
| Spinach | Sow outdoors (fall) | Jul 4 – Aug 8 |
| Radishes | Sow outdoors (spring) | Apr 15 – Jun 5 |
| Radishes | Sow outdoors (fall) | Jun 17 – Aug 18 |
| Kale | Sow outdoors (spring) | May 2 – May 22 |
| Kale | Sow outdoors (fall) | Jun 10 – Jul 18 |
| Carrots | Sow outdoors (spring) | May 16 – Jul 1 |
| Carrots | Sow outdoors (fall) | May 18 – Jul 3 |
| Garlic | Plant outdoors (fall) | Sep 17 – Oct 18 |
Where these dates come from
ZIP code 58205 is matched to the NOAA station Grand Forks Intl Ap, ND, 14.6 km away, at 842 ft elevation (47 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Grand Forks Intl Ap, ND (used) | 842 ft | May 16 | Sep 27 |
| Grand Forks Univ (Nws), ND | 830 ft | May 10 | Oct 1 |
| Larimore 4Sw, ND | 1,152 ft | May 11 | Sep 28 |
| Petersburg 2 N, ND | 1,532 ft | May 11 | Sep 28 |
Frost dates near Grand Forks Afb
- Grand Forks Afb, ND 58204 · last May 16, first Sep 27
- Mekinock, ND 58258 · last May 16, first Sep 27
- Emerado, ND 58228 · last May 16, first Sep 27
- Arvilla, ND 58214 · last May 16, first Sep 27
- Gilby, ND 58235 · last May 16, first Sep 27
- Larimore, ND 58251 · last May 11, first Sep 28
- Manvel, ND 58256 · last May 16, first Sep 27
- Grand Forks, ND 58202 · last May 10, first Oct 1
Frequently asked questions
- When is the last frost in Grand Forks Afb, ND?
- For ZIP code 58205, the average last spring frost (32°F) is May 16, based on NOAA 1991-2020 climate normals for the Grand Forks Intl Ap, ND weather station. There is a 1-in-10 chance of a frost after May 31.
- When is the first frost in Grand Forks Afb, ND?
- The average first fall frost (32°F) is September 27. There is a 1-in-10 chance of frost by September 15, so tender plants are at risk from that point on.
- How long is the growing season in 58205?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 133 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.