Frost dates for 58634Grassy Butte, ND
The average last spring frost in Grassy Butte is May 18 and the average first fall frost is September 23, giving a typical growing season of about 125 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 18
- Average first fall frost
- Sep 23
- Growing season
- 125 days
Safer after Jun 1 (1-in-10 risk)
Possible by Sep 9 (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 17 · May 30 · Jun 21 | Aug 30 · Sep 15 · Sep 26 | 105 days | 100% |
| Frost / freeze (32°F) | May 7 · May 18 · Jun 1 | Sep 9 · Sep 23 · Oct 5 | 125 days | 100% |
| Hard freeze (28°F) | Apr 26 · May 9 · May 22 | Sep 18 · Oct 3 · Oct 16 | 145 days | 100% |
Planting calendar for Grassy Butte
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 17 – Jun 23 |
| Tomatoes | Transplant outdoors | Jun 3 – Jun 3 |
| Peppers | Start seeds indoors | Apr 17 – May 18 |
| Peppers | Transplant outdoors | Jun 17 – Jul 18 |
| Eggplant | Start seeds indoors | May 4 – Jun 2 |
| Eggplant | Transplant outdoors | Jun 17 – Jul 18 |
| Cucumbers | Sow outdoors | Jun 17 – Jun 13 |
| Summer squash | Sow outdoors | Jun 3 – Jul 18 |
| Winter squash & pumpkins | Sow outdoors | Jun 17 – Jul 18 |
| Snap beans | Sow outdoors | Jun 3 – Jul 6 |
| Sweet corn | Sow outdoors | Jun 3 – Jun 3 |
| Watermelon & cantaloupe | Sow outdoors | Jun 17 – Jul 18 |
| Okra | Sow outdoors | Jun 10 – Jul 3 |
| Peas | Sow outdoors (spring) | Apr 17 – Jun 2 |
| Potatoes | Plant outdoors (spring) | Apr 17 – Jun 17 |
| Onions | Start seeds indoors (spring) | Mar 6 – Apr 2 |
| Onions | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (spring) | Mar 30 – May 3 |
| Broccoli | Transplant outdoors (spring) | May 4 – Jun 2 |
| Broccoli | Start seeds indoors (fall) | May 24 – Jun 3 |
| Broccoli | Transplant outdoors (fall) | Jun 23 – Jul 4 |
| Cabbage | Start seeds indoors (spring) | Mar 20 – Apr 17 |
| Cabbage | Transplant outdoors (spring) | Apr 17 – May 18 |
| Cabbage | Start seeds indoors (fall) | May 14 – Jun 13 |
| Cabbage | Transplant outdoors (fall) | Jun 13 – Jul 14 |
| Leaf lettuce | Sow outdoors (spring) | Apr 17 – Jul 3 |
| Leaf lettuce | Sow outdoors (fall) | Jun 13 – Jul 30 |
| Spinach | Sow outdoors (spring) | Apr 10 – May 24 |
| Spinach | Sow outdoors (fall) | Jun 30 – Aug 4 |
| Radishes | Sow outdoors (spring) | Apr 17 – Jun 7 |
| Radishes | Sow outdoors (fall) | Jun 13 – Aug 14 |
| Kale | Sow outdoors (spring) | May 4 – May 24 |
| Kale | Sow outdoors (fall) | Jun 6 – Jul 14 |
| Carrots | Sow outdoors (spring) | May 18 – Jul 3 |
| Carrots | Sow outdoors (fall) | May 14 – Jun 29 |
| Garlic | Plant outdoors (fall) | Sep 13 – Oct 14 |
Where these dates come from
ZIP code 58634 is matched to the NOAA station Grassy Butte 2Ene, ND, 8.1 km away, at 2,670 ft elevation (26 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Grassy Butte 2Ene, ND (used) | 2,670 ft | May 18 | Sep 23 |
| Watford City 14S, ND | 2,027 ft | May 22 | Sep 17 |
| Fairfield, ND | 2,750 ft | May 12 | Sep 28 |
| Watford City, ND | 2,170 ft | May 9 | Sep 27 |
Frost dates near Grassy Butte
- Fairfield, ND 58627 · last May 12, first Sep 28
- Killdeer, ND 58640 · last May 21, first Sep 23
- Watford City, ND 58854 · last May 9, first Sep 27
- Arnegard, ND 58835 · last May 9, first Sep 27
- Alexander, ND 58831 · last May 9, first Sep 27
- Dunn Center, ND 58626 · last May 20, first Sep 21
- Mandaree, ND 58757 · last May 20, first Sep 20
- Manning, ND 58642 · last May 18, first Sep 24
Frequently asked questions
- When is the last frost in Grassy Butte, ND?
- For ZIP code 58634, the average last spring frost (32°F) is May 18, based on NOAA 1991-2020 climate normals for the Grassy Butte 2Ene, ND weather station. There is a 1-in-10 chance of a frost after June 1.
- When is the first frost in Grassy Butte, ND?
- The average first fall frost (32°F) is September 23. There is a 1-in-10 chance of frost by September 9, so tender plants are at risk from that point on.
- How long is the growing season in 58634?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 125 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.