Frost dates for 58803Williston, ND
The average last spring frost in Williston is May 21 and the average first fall frost is September 21, giving a typical growing season of about 123 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 21
- Average first fall frost
- Sep 21
- Growing season
- 123 days
Safer after Jun 3 (1-in-10 risk)
Possible by Sep 9 (1-in-10 risk)
Last frost typically in 199 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 18 · May 29 · Jun 16 | Sep 1 · Sep 12 · Sep 23 | 105 days | 100% |
| Frost / freeze (32°F) | May 8 · May 21 · Jun 3 | Sep 9 · Sep 21 · Oct 2 | 123 days | 100% |
| Hard freeze (28°F) | Apr 29 · May 11 · May 25 | Sep 16 · Sep 28 · Oct 11 | 140 days | 100% |
Planting calendar for Williston
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 20 – Jun 26 |
| Tomatoes | Transplant outdoors | Jun 6 – Jun 1 |
| Peppers | Start seeds indoors | Apr 20 – May 21 |
| Peppers | Transplant outdoors | Jun 20 – Jul 21 |
| Eggplant | Start seeds indoors | May 7 – Jun 5 |
| Eggplant | Transplant outdoors | Jun 20 – Jul 21 |
| Cucumbers | Sow outdoors | Jun 20 – Jun 11 |
| Summer squash | Sow outdoors | Jun 6 – Jul 21 |
| Winter squash & pumpkins | Sow outdoors | Jun 20 – Jul 21 |
| Snap beans | Sow outdoors | Jun 6 – Jul 4 |
| Sweet corn | Sow outdoors | Jun 6 – Jun 1 |
| Watermelon & cantaloupe | Sow outdoors | Jun 20 – Jul 21 |
| Okra | Sow outdoors | Jun 13 – Jul 6 |
| Peas | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Potatoes | Plant outdoors (spring) | Apr 20 – Jun 20 |
| Onions | Start seeds indoors (spring) | Mar 9 – Apr 5 |
| Onions | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (spring) | Apr 2 – May 6 |
| Broccoli | Transplant outdoors (spring) | May 7 – Jun 5 |
| Broccoli | Start seeds indoors (fall) | May 22 – Jun 1 |
| Broccoli | Transplant outdoors (fall) | Jun 21 – Jul 2 |
| Cabbage | Start seeds indoors (spring) | Mar 23 – Apr 20 |
| Cabbage | Transplant outdoors (spring) | Apr 20 – May 21 |
| Cabbage | Start seeds indoors (fall) | May 12 – Jun 11 |
| Cabbage | Transplant outdoors (fall) | Jun 11 – Jul 12 |
| Leaf lettuce | Sow outdoors (spring) | Apr 20 – Jul 6 |
| Leaf lettuce | Sow outdoors (fall) | Jun 11 – Jul 28 |
| Spinach | Sow outdoors (spring) | Apr 13 – May 27 |
| Spinach | Sow outdoors (fall) | Jun 28 – Aug 2 |
| Radishes | Sow outdoors (spring) | Apr 20 – Jun 10 |
| Radishes | Sow outdoors (fall) | Jun 11 – Aug 12 |
| Kale | Sow outdoors (spring) | May 7 – May 27 |
| Kale | Sow outdoors (fall) | Jun 4 – Jul 12 |
| Carrots | Sow outdoors (spring) | May 21 – Jul 6 |
| Carrots | Sow outdoors (fall) | May 12 – Jun 27 |
| Garlic | Plant outdoors (fall) | Sep 11 – Oct 12 |
Where these dates come from
ZIP code 58803 is matched to the NOAA station Williston Sloulin Intl Ap, ND, 3.3 km away, at 1,902 ft elevation (22 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Williston Sloulin Intl Ap, ND (used) | 1,902 ft | May 21 | Sep 21 |
| Williston Exp Farm, ND | 2,105 ft | May 13 | Sep 26 |
| Watford City, ND | 2,170 ft | May 9 | Sep 27 |
| Keene 3S, ND | 2,470 ft | May 20 | Sep 20 |
Frost dates near Williston
- Williston, ND 58802 · last May 21, first Sep 21
- Trenton, ND 58853 · last May 21, first Sep 21
- Epping, ND 58843 · last May 13, first Sep 26
- Ray, ND 58849 · last May 11, first Sep 26
- Alexander, ND 58831 · last May 9, first Sep 27
- Arnegard, ND 58835 · last May 9, first Sep 27
- Bainville, MT 59212 · last May 21, first Sep 20
- Cartwright, ND 58838 · last May 11, first Sep 27
Frequently asked questions
- When is the last frost in Williston, ND?
- For ZIP code 58803, the average last spring frost (32°F) is May 21, based on NOAA 1991-2020 climate normals for the Williston Sloulin Intl Ap, ND weather station. There is a 1-in-10 chance of a frost after June 3.
- When is the first frost in Williston, ND?
- The average first fall frost (32°F) is September 21. 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 58803?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 123 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.