Napoleon, ND frost dates
Last spring frostMay 13median date
First fall frostSep 28median date
Growing season138 daysfrost-free
Hardiness zone4aZone 4a
How Napoleon compares
- In 8 years out of 10, the last spring frost in Napoleon falls between May 1 and May 26, a 25-day window. The first fall frost falls between September 15 and October 11.
- The median last frost is 1 day later than the North Dakota median of May 12.
- Its 138-day growing season is longer than 44% 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 188 nights a year at or below 32°F.
- Compared with Bismarck, ND, 83 km away, the last frost here is 3 days later than there and the growing season is 5 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 1 |
| 50% (median) | May 13 |
| 10% (safe for tender plants) | May 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 15 |
| 50% (median) | September 28 |
| 90% (late) | October 11 |
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 Napoleon, ND
Napoleon, ND frost dates — last frost May 13, first frost Sep 28, zone 4a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 18 to Mar 4Transplant outside: Apr 15 to Apr 29
Start indoors: Mar 4 to Mar 18Transplant outside: May 27 to Jun 10
Start indoors: Mar 4 to Mar 18Transplant outside: May 27 to Jun 10
Start indoors: Mar 18 to Apr 1Transplant outside: May 20 to Jun 3
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 22 to May 6Sow outdoors: Apr 15 to May 20Plant for fall: Aug 3 to Aug 31
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 15 to Apr 29Sow outdoors: Apr 15 to Apr 29Plant for fall: Jul 20 to Aug 10
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 29 to May 13Plant for fall: Jun 22 to Jul 13
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 22 to May 6Plant for fall: Jun 22 to Jul 13
Start indoors: Mar 18 to Apr 1Transplant outside: Apr 29 to May 13Plant for fall: Jun 22 to Jul 13
Start indoors: Apr 1 to Apr 15Transplant outside: Jun 3 to Jun 17Sow outdoors: Jun 3 to Jun 17
Start indoors: Apr 1 to Apr 15Transplant outside: May 20 to Jun 3
Sow outdoors: Apr 1 to Apr 22Plant for fall: Jul 6 to Jul 27
Sow outdoors: Apr 1 to Apr 22Plant for fall: Aug 3 to Aug 24
Sow outdoors: Apr 8 to May 20Plant for fall: Aug 17 to Sep 7
Start indoors: Apr 15 to Apr 22Transplant outside: May 27 to Jun 3Sow outdoors: May 20 to Jun 3Plant for fall: Jul 13 to Jul 27
Start indoors: Apr 15 to Apr 22Sow outdoors: May 20 to Jun 3Plant for fall: Jul 20 to Aug 3
Start indoors: Apr 15 to Apr 22Sow outdoors: May 20 to Jun 3
Start indoors: Apr 15 to Apr 22Transplant outside: May 27 to Jun 10
Sow outdoors: Apr 22 to May 20Plant for fall: Jul 6 to Jul 20
Sow outdoors: Apr 22 to May 20Plant for fall: Jul 20 to Aug 3
Sow outdoors: Apr 22 to May 13
Sow outdoors: Apr 29 to May 27Plant for fall: Jul 20 to Aug 3
Sow outdoors: Apr 29 to May 20Plant for fall: Aug 3 to Aug 24
Sow outdoors: May 20 to Jun 10Plant for fall: Jul 13 to Jul 27
Sow outdoors: May 20 to Jun 3
Transplant outside: May 27 to Jun 17
Plant for fall: Sep 14 to Oct 19
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Napoleon, ND
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 18 – Mar 4 | Apr 15 – Apr 29 | — | — |
| Peppers | Mar 4 – Mar 18 | May 27 – Jun 10 | — | — |
| Eggplant | Mar 4 – Mar 18 | May 27 – Jun 10 | — | — |
| Tomatoes | Mar 18 – Apr 1 | May 20 – Jun 3 | — | — |
| Lettuce | Mar 18 – Apr 1 | Apr 22 – May 6 | Apr 15 – May 20 | Aug 3 – Aug 31 |
| Kale | Mar 18 – Apr 1 | Apr 15 – Apr 29 | Apr 15 – Apr 29 | Jul 20 – Aug 10 |
| Broccoli | Mar 18 – Apr 1 | Apr 29 – May 13 | — | Jun 22 – Jul 13 |
| Cabbage | Mar 18 – Apr 1 | Apr 22 – May 6 | — | Jun 22 – Jul 13 |
| Cauliflower | Mar 18 – Apr 1 | Apr 29 – May 13 | — | Jun 22 – Jul 13 |
| Okra | Apr 1 – Apr 15 | Jun 3 – Jun 17 | Jun 3 – Jun 17 | — |
| Basil | Apr 1 – Apr 15 | May 20 – Jun 3 | — | — |
| Peas | — | — | Apr 1 – Apr 22 | Jul 6 – Jul 27 |
| Spinach | — | — | Apr 1 – Apr 22 | Aug 3 – Aug 24 |
| Radishes | — | — | Apr 8 – May 20 | Aug 17 – Sep 7 |
| Cucumbers | Apr 15 – Apr 22 | May 27 – Jun 3 | May 20 – Jun 3 | Jul 13 – Jul 27 |
| Zucchini & Summer Squash | Apr 15 – Apr 22 | — | May 20 – Jun 3 | Jul 20 – Aug 3 |
| Winter Squash & Pumpkins | Apr 15 – Apr 22 | — | May 20 – Jun 3 | — |
| Melons & Watermelon | Apr 15 – Apr 22 | May 27 – Jun 10 | — | — |
| Carrots | — | — | Apr 22 – May 20 | Jul 6 – Jul 20 |
| Beets | — | — | Apr 22 – May 20 | Jul 20 – Aug 3 |
| Potatoes | — | — | Apr 22 – May 13 | — |
| Swiss Chard | — | — | Apr 29 – May 27 | Jul 20 – Aug 3 |
| Cilantro | — | — | Apr 29 – May 20 | Aug 3 – Aug 24 |
| Green Beans | — | — | May 20 – Jun 10 | Jul 13 – Jul 27 |
| Sweet Corn | — | — | May 20 – Jun 3 | — |
| Sweet Potatoes | — | May 27 – Jun 17 | — | — |
| Garlic | — | — | — | Sep 14 – Oct 19 |
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 Napoleon, ND weather station, 2 km away (elevation 1,982 ft (604 m)).
Frost dates near Napoleon
- Kintyre May 13 · Sep 28
- Braddock May 11 · Sep 29
- Wishek May 13 · Sep 27
- Hazelton May 12 · Sep 27
- Tappen May 14 · Sep 27
- Lehr May 13 · Sep 27
- Steele May 15 · Sep 25
- Dawson May 15 · Sep 25
- Streeter May 13 · Sep 30
- Gackle May 6 · Oct 4
Frequently asked questions
When is the last frost in Napoleon, ND?
The median last spring frost in Napoleon, ND is May 13. There is still about a 10% chance of frost after May 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Napoleon, ND?
The median first fall frost is September 28, with about a 10% chance of frost before September 15.
How long is the growing season in Napoleon, ND?
About 138 days between the median last spring frost and first fall frost.
What planting zone is Napoleon, ND?
Napoleon, ND is in USDA hardiness zone 4a.