Frost Dates for Williston, ND
In Williston, ND, the average last spring frost is around May 21 and the average first fall frost around Sep 21, for a growing season of about 123 days. For frost-tender plants, wait until Jun 3, when the chance of frost drops to 10%.
Based on NOAA 1991–2020 records from the Williston Sloulin Intl. Airport, ND weather station, 1 mile away, elevation 1,902 ft. Frost can come earlier in low spots and valleys and later near cities and large lakes.
Frost probability by date
Chance of a 32°F frost after the spring date, or before the fall date.
| Chance | Last spring frost | First fall frost |
|---|---|---|
| 10% | Jun 3 | Sep 9 |
| 20% | May 29 | Sep 13 |
| 30% | May 26 | Sep 17 |
| 40% | May 24 | Sep 19 |
| 50% | May 21 | Sep 21 |
| 60% | May 18 | Sep 23 |
| 70% | May 16 | Sep 25 |
| 80% | May 13 | Sep 28 |
| 90% | May 8 | Oct 2 |
Light frost vs. hard freeze
Average (50%) dates for each temperature. Tender plants are damaged at 36°F; most hardy crops survive until 28°F.
| Temperature | Last in spring | First in fall |
|---|---|---|
| Light frost (36°F) | May 29 | Sep 12 |
| Frost / freeze (32°F) | May 21 | Sep 21 |
| Hard freeze (28°F) | May 11 | Sep 28 |
Planting calendar for Williston
Transplant May 28 – Jun 11
Transplant Jun 4 – Jun 18
Transplant Jun 4 – Jun 18
Transplant May 28 – Jun 11
Sow or transplant May 28 – Jun 11
Sow or transplant May 28 – Jun 11
Sow or transplant Jun 4 – Jun 18
Sow or transplant Apr 23 – May 7
Fall sowing Jul 27 – Aug 24
Fall sowing Jul 27 – Aug 17
Fall sowing Jul 13 – Jul 27
Sow or transplant Apr 23 – May 7
Fall sowing Jul 13 – Aug 10
Transplant May 7 – May 21
Fall sowing Jun 29 – Jul 13
Transplant Apr 30 – May 14
Fall sowing Jun 29 – Jul 13
Fall sowing Jun 29 – Jul 13
Fall sowing Aug 10 – Aug 31
Fall sowing Jul 13 – Jul 27
Plant Apr 23 – May 7
Based on the average last frost (May 21) and first frost (Sep 21). The dashed lines mark those dates. Seed packets list days to maturity; adjust for your varieties.