Thompson, ND frost dates
Last spring frostMay 10median date
First fall frostOct 1median date
Growing season144 daysfrost-free
Hardiness zone4aZone 4a
How Thompson compares
- In 8 years out of 10, the last spring frost in Thompson falls between April 28 and May 24, a 26-day window. The first fall frost falls between September 20 and October 15.
- The median last frost is 2 days earlier than the North Dakota median of May 12.
- Its 144-day growing season is longer than 76% of the 372 North Dakota places with a regular frost season (state median 139 days).
- The last frost is typical for zone 4a, where the median is May 12.
- The weather station records an average of 179 nights a year at or below 32°F.
- Thompson shares its weather station with Grand Forks, ND, 16 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 28 |
| 50% (median) | May 10 |
| 10% (safe for tender plants) | May 24 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 20 |
| 50% (median) | October 1 |
| 90% (late) | October 15 |
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 Thompson, ND
Thompson, ND frost dates — last frost May 10, first frost Oct 1, zone 4a. whenisthelastfrost.com
Crop
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Start indoors: Feb 15 to Mar 1Transplant outside: Apr 12 to Apr 26
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 15 to Mar 29Transplant outside: May 17 to May 31
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Sow outdoors: Apr 12 to May 17Plant for fall: Aug 6 to Sep 3
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 12 to Apr 26Sow outdoors: Apr 12 to Apr 26Plant for fall: Jul 23 to Aug 13
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 25 to Jul 16
Start indoors: Mar 29 to Apr 12Transplant outside: May 31 to Jun 14Sow outdoors: May 31 to Jun 14
Start indoors: Mar 29 to Apr 12Transplant outside: May 17 to May 31
Sow outdoors: Mar 29 to Apr 19Plant for fall: Jul 9 to Jul 30
Sow outdoors: Mar 29 to Apr 19Plant for fall: Aug 6 to Aug 27
Sow outdoors: Apr 5 to May 17Plant for fall: Aug 20 to Sep 10
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to May 31Sow outdoors: May 17 to May 31Plant for fall: Jul 16 to Jul 30
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31Plant for fall: Jul 23 to Aug 6
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to Jun 7
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 9 to Jul 23
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 19 to May 10
Sow outdoors: Apr 26 to May 24Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 26 to May 17Plant for fall: Aug 6 to Aug 27
Sow outdoors: May 17 to Jun 7Plant for fall: Jul 16 to Jul 30
Sow outdoors: May 17 to May 31
Transplant outside: May 24 to Jun 14
Plant for fall: Sep 17 to Oct 22
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Thompson, ND
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 15 – Mar 1 | Apr 12 – Apr 26 | — | — |
| Peppers | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Eggplant | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Tomatoes | Mar 15 – Mar 29 | May 17 – May 31 | — | — |
| Lettuce | Mar 15 – Mar 29 | Apr 19 – May 3 | Apr 12 – May 17 | Aug 6 – Sep 3 |
| Kale | Mar 15 – Mar 29 | Apr 12 – Apr 26 | Apr 12 – Apr 26 | Jul 23 – Aug 13 |
| Broccoli | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 25 – Jul 16 |
| Cabbage | Mar 15 – Mar 29 | Apr 19 – May 3 | — | Jun 25 – Jul 16 |
| Cauliflower | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 25 – Jul 16 |
| Okra | Mar 29 – Apr 12 | May 31 – Jun 14 | May 31 – Jun 14 | — |
| Basil | Mar 29 – Apr 12 | May 17 – May 31 | — | — |
| Peas | — | — | Mar 29 – Apr 19 | Jul 9 – Jul 30 |
| Spinach | — | — | Mar 29 – Apr 19 | Aug 6 – Aug 27 |
| Radishes | — | — | Apr 5 – May 17 | Aug 20 – Sep 10 |
| Cucumbers | Apr 12 – Apr 19 | May 24 – May 31 | May 17 – May 31 | Jul 16 – Jul 30 |
| Zucchini & Summer Squash | Apr 12 – Apr 19 | — | May 17 – May 31 | Jul 23 – Aug 6 |
| Winter Squash & Pumpkins | Apr 12 – Apr 19 | — | May 17 – May 31 | — |
| Melons & Watermelon | Apr 12 – Apr 19 | May 24 – Jun 7 | — | — |
| Carrots | — | — | Apr 19 – May 17 | Jul 9 – Jul 23 |
| Beets | — | — | Apr 19 – May 17 | Jul 23 – Aug 6 |
| Potatoes | — | — | Apr 19 – May 10 | — |
| Swiss Chard | — | — | Apr 26 – May 24 | Jul 23 – Aug 6 |
| Cilantro | — | — | Apr 26 – May 17 | Aug 6 – Aug 27 |
| Green Beans | — | — | May 17 – Jun 7 | Jul 16 – Jul 30 |
| Sweet Corn | — | — | May 17 – May 31 | — |
| Sweet Potatoes | — | May 24 – Jun 14 | — | — |
| Garlic | — | — | — | Sep 17 – Oct 22 |
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 Grand Forks Univ (Nws), ND weather station, 16 km away (elevation 830 ft (253 m)).
Frost dates near Thompson
- Reynolds May 10 · Oct 1
- Grand Forks May 10 · Oct 1
- Buxton May 2 · Oct 9
- Emerado May 16 · Sep 27
- Cummings May 2 · Oct 9
- Grand Forks Afb May 16 · Sep 27
- Hatton May 13 · Sep 27
- Arvilla May 11 · Sep 28
- Mayville May 13 · Sep 27
- Manvel May 16 · Sep 27
Frequently asked questions
When is the last frost in Thompson, ND?
The median last spring frost in Thompson, ND is May 10. There is still about a 10% chance of frost after May 24, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Thompson, ND?
The median first fall frost is October 1, with about a 10% chance of frost before September 20.
How long is the growing season in Thompson, ND?
About 144 days between the median last spring frost and first fall frost.
What planting zone is Thompson, ND?
Thompson, ND is in USDA hardiness zone 4a.