Williston, ND frost dates
Last spring frostMay 21median date
First fall frostSep 21median date
Growing season123 daysfrost-free
Hardiness zone4aZone 4a
How Williston compares
- In 8 years out of 10, the last spring frost in Williston falls between May 8 and June 3, a 26-day window. The first fall frost falls between September 9 and October 2.
- The median last frost is 9 days later than the North Dakota median of May 12.
- Its 123-day growing season is longer than 6% of the 372 North Dakota places with a regular frost season (state median 139 days).
- The last frost is 9 days later than the zone 4a median of May 12. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4a chart.
- The weather station records an average of 191 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 8 |
| 50% (median) | May 21 |
| 10% (safe for tender plants) | June 3 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 9 |
| 50% (median) | September 21 |
| 90% (late) | October 2 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Williston, ND
Williston, ND frost dates — last frost May 21, first frost Sep 21, zone 4a. whenisthelastfrost.com
Crop
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Start indoors: Feb 26 to Mar 12Transplant outside: Apr 23 to May 7
Start indoors: Mar 12 to Mar 26Transplant outside: Jun 4 to Jun 18
Start indoors: Mar 12 to Mar 26Transplant outside: Jun 4 to Jun 18
Start indoors: Mar 26 to Apr 9Transplant outside: May 28 to Jun 11
Start indoors: Mar 26 to Apr 9Transplant outside: Apr 30 to May 14Sow outdoors: Apr 23 to May 28Plant for fall: Jul 27 to Aug 24
Start indoors: Mar 26 to Apr 9Transplant outside: Apr 23 to May 7Sow outdoors: Apr 23 to May 7Plant for fall: Jul 13 to Aug 3
Start indoors: Mar 26 to Apr 9Transplant outside: May 7 to May 21Plant for fall: Jun 15 to Jul 6
Start indoors: Mar 26 to Apr 9Transplant outside: Apr 30 to May 14Plant for fall: Jun 15 to Jul 6
Start indoors: Mar 26 to Apr 9Transplant outside: May 7 to May 21Plant for fall: Jun 15 to Jul 6
Start indoors: Apr 9 to Apr 23Transplant outside: Jun 11 to Jun 25Sow outdoors: Jun 11 to Jun 25
Start indoors: Apr 9 to Apr 23Transplant outside: May 28 to Jun 11
Sow outdoors: Apr 9 to Apr 30Plant for fall: Jun 29 to Jul 20
Sow outdoors: Apr 9 to Apr 30Plant for fall: Jul 27 to Aug 17
Sow outdoors: Apr 16 to May 28Plant for fall: Aug 10 to Aug 31
Start indoors: Apr 23 to Apr 30Transplant outside: Jun 4 to Jun 11Sow outdoors: May 28 to Jun 11Plant for fall: Jul 6 to Jul 20
Start indoors: Apr 23 to Apr 30Sow outdoors: May 28 to Jun 11Plant for fall: Jul 13 to Jul 27
Start indoors: Apr 23 to Apr 30Sow outdoors: May 28 to Jun 11
Start indoors: Apr 23 to Apr 30Transplant outside: Jun 4 to Jun 18
Sow outdoors: Apr 30 to May 28Plant for fall: Jun 29 to Jul 13
Sow outdoors: Apr 30 to May 28Plant for fall: Jul 13 to Jul 27
Sow outdoors: Apr 30 to May 21
Sow outdoors: May 7 to Jun 4Plant for fall: Jul 13 to Jul 27
Sow outdoors: May 7 to May 28Plant for fall: Jul 27 to Aug 17
Sow outdoors: May 28 to Jun 18Plant for fall: Jul 6 to Jul 20
Sow outdoors: May 28 to Jun 11
Transplant outside: Jun 4 to Jun 25
Plant for fall: Sep 7 to Oct 12
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Williston, ND
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 26 – Mar 12 | Apr 23 – May 7 | — | — |
| Peppers | Mar 12 – Mar 26 | Jun 4 – Jun 18 | — | — |
| Eggplant | Mar 12 – Mar 26 | Jun 4 – Jun 18 | — | — |
| Tomatoes | Mar 26 – Apr 9 | May 28 – Jun 11 | — | — |
| Lettuce | Mar 26 – Apr 9 | Apr 30 – May 14 | Apr 23 – May 28 | Jul 27 – Aug 24 |
| Kale | Mar 26 – Apr 9 | Apr 23 – May 7 | Apr 23 – May 7 | Jul 13 – Aug 3 |
| Broccoli | Mar 26 – Apr 9 | May 7 – May 21 | — | Jun 15 – Jul 6 |
| Cabbage | Mar 26 – Apr 9 | Apr 30 – May 14 | — | Jun 15 – Jul 6 |
| Cauliflower | Mar 26 – Apr 9 | May 7 – May 21 | — | Jun 15 – Jul 6 |
| Okra | Apr 9 – Apr 23 | Jun 11 – Jun 25 | Jun 11 – Jun 25 | — |
| Basil | Apr 9 – Apr 23 | May 28 – Jun 11 | — | — |
| Peas | — | — | Apr 9 – Apr 30 | Jun 29 – Jul 20 |
| Spinach | — | — | Apr 9 – Apr 30 | Jul 27 – Aug 17 |
| Radishes | — | — | Apr 16 – May 28 | Aug 10 – Aug 31 |
| Cucumbers | Apr 23 – Apr 30 | Jun 4 – Jun 11 | May 28 – Jun 11 | Jul 6 – Jul 20 |
| Zucchini & Summer Squash | Apr 23 – Apr 30 | — | May 28 – Jun 11 | Jul 13 – Jul 27 |
| Winter Squash & Pumpkins | Apr 23 – Apr 30 | — | May 28 – Jun 11 | — |
| Melons & Watermelon | Apr 23 – Apr 30 | Jun 4 – Jun 18 | — | — |
| Carrots | — | — | Apr 30 – May 28 | Jun 29 – Jul 13 |
| Beets | — | — | Apr 30 – May 28 | Jul 13 – Jul 27 |
| Potatoes | — | — | Apr 30 – May 21 | — |
| Swiss Chard | — | — | May 7 – Jun 4 | Jul 13 – Jul 27 |
| Cilantro | — | — | May 7 – May 28 | Jul 27 – Aug 17 |
| Green Beans | — | — | May 28 – Jun 18 | Jul 6 – Jul 20 |
| Sweet Corn | — | — | May 28 – Jun 11 | — |
| Sweet Potatoes | — | Jun 4 – Jun 25 | — | — |
| Garlic | — | — | — | Sep 7 – Oct 12 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Williston Sloulin Intl Ap, ND weather station, about 1 km away (elevation 1,903 ft (580 m)).
ZIP codes in Williston: 58801 58802 58803
Frost dates near Williston
- Trenton May 13 · Sep 26
- Epping May 21 · Sep 21
- Ray May 11 · Sep 26
- Alexander May 9 · Sep 27
- Arnegard May 9 · Sep 27
- Grenora May 16 · Sep 18
- Zahl May 18 · Sep 20
- Alamo May 18 · Sep 20
- Cartwright May 11 · Sep 27
- Watford City May 9 · Sep 27
Frequently asked questions
When is the last frost in Williston, ND?
The median last spring frost in Williston, ND is May 21. There is still about a 10% chance of frost after June 3, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Williston, ND?
The median first fall frost is September 21, with about a 10% chance of frost before September 9.
How long is the growing season in Williston, ND?
About 123 days between the median last spring frost and first fall frost.
What planting zone is Williston, ND?
Williston, ND is in USDA hardiness zone 4a.