Moorcroft, WY frost dates
Last spring frostMay 23median date
First fall frostSep 20median date
Growing season120 daysfrost-free
Hardiness zone4bZone 4b
How Moorcroft compares
- In 8 years out of 10, the last spring frost in Moorcroft falls between May 12 and June 6, a 25-day window. The first fall frost falls between September 4 and October 4.
- The median last frost is 2 days later than the Wyoming median of May 21.
- Its 120-day growing season is longer than 33% of the 153 Wyoming places with a regular frost season (state median 125 days).
- The last frost is 15 days later than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 201 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 12 |
| 50% (median) | May 23 |
| 10% (safe for tender plants) | June 6 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 4 |
| 50% (median) | September 20 |
| 90% (late) | October 4 |
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 Moorcroft, WY
Moorcroft, WY frost dates — last frost May 23, first frost Sep 20, zone 4b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 28 to Mar 14Transplant outside: Apr 25 to May 9
Start indoors: Mar 14 to Mar 28Transplant outside: Jun 6 to Jun 20
Start indoors: Mar 14 to Mar 28Transplant outside: Jun 6 to Jun 20
Start indoors: Mar 28 to Apr 11Transplant outside: May 30 to Jun 13
Start indoors: Mar 28 to Apr 11Transplant outside: May 2 to May 16Sow outdoors: Apr 25 to May 30Plant for fall: Jul 26 to Aug 23
Start indoors: Mar 28 to Apr 11Transplant outside: Apr 25 to May 9Sow outdoors: Apr 25 to May 9Plant for fall: Jul 12 to Aug 2
Start indoors: Mar 28 to Apr 11Transplant outside: May 9 to May 23Plant for fall: Jun 14 to Jul 5
Start indoors: Mar 28 to Apr 11Transplant outside: May 2 to May 16Plant for fall: Jun 14 to Jul 5
Start indoors: Mar 28 to Apr 11Transplant outside: May 9 to May 23Plant for fall: Jun 14 to Jul 5
Start indoors: Apr 11 to Apr 25Transplant outside: Jun 13 to Jun 27Sow outdoors: Jun 13 to Jun 27
Start indoors: Apr 11 to Apr 25Transplant outside: May 30 to Jun 13
Sow outdoors: Apr 11 to May 2Plant for fall: Jun 28 to Jul 19
Sow outdoors: Apr 11 to May 2Plant for fall: Jul 26 to Aug 16
Sow outdoors: Apr 18 to May 30Plant for fall: Aug 9 to Aug 30
Start indoors: Apr 25 to May 2Transplant outside: Jun 6 to Jun 13Sow outdoors: May 30 to Jun 13Plant for fall: Jul 5 to Jul 19
Start indoors: Apr 25 to May 2Sow outdoors: May 30 to Jun 13Plant for fall: Jul 12 to Jul 26
Start indoors: Apr 25 to May 2Sow outdoors: May 30 to Jun 13
Start indoors: Apr 25 to May 2Transplant outside: Jun 6 to Jun 20
Sow outdoors: May 2 to May 30Plant for fall: Jun 28 to Jul 12
Sow outdoors: May 2 to May 30Plant for fall: Jul 12 to Jul 26
Sow outdoors: May 2 to May 23
Sow outdoors: May 9 to Jun 6Plant for fall: Jul 12 to Jul 26
Sow outdoors: May 9 to May 30Plant for fall: Jul 26 to Aug 16
Sow outdoors: May 30 to Jun 20Plant for fall: Jul 5 to Jul 19
Sow outdoors: May 30 to Jun 13
Transplant outside: Jun 6 to Jun 27
Plant for fall: Sep 6 to Oct 11
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Moorcroft, WY
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 28 – Mar 14 | Apr 25 – May 9 | — | — |
| Peppers | Mar 14 – Mar 28 | Jun 6 – Jun 20 | — | — |
| Eggplant | Mar 14 – Mar 28 | Jun 6 – Jun 20 | — | — |
| Tomatoes | Mar 28 – Apr 11 | May 30 – Jun 13 | — | — |
| Lettuce | Mar 28 – Apr 11 | May 2 – May 16 | Apr 25 – May 30 | Jul 26 – Aug 23 |
| Kale | Mar 28 – Apr 11 | Apr 25 – May 9 | Apr 25 – May 9 | Jul 12 – Aug 2 |
| Broccoli | Mar 28 – Apr 11 | May 9 – May 23 | — | Jun 14 – Jul 5 |
| Cabbage | Mar 28 – Apr 11 | May 2 – May 16 | — | Jun 14 – Jul 5 |
| Cauliflower | Mar 28 – Apr 11 | May 9 – May 23 | — | Jun 14 – Jul 5 |
| Okra | Apr 11 – Apr 25 | Jun 13 – Jun 27 | Jun 13 – Jun 27 | — |
| Basil | Apr 11 – Apr 25 | May 30 – Jun 13 | — | — |
| Peas | — | — | Apr 11 – May 2 | Jun 28 – Jul 19 |
| Spinach | — | — | Apr 11 – May 2 | Jul 26 – Aug 16 |
| Radishes | — | — | Apr 18 – May 30 | Aug 9 – Aug 30 |
| Cucumbers | Apr 25 – May 2 | Jun 6 – Jun 13 | May 30 – Jun 13 | Jul 5 – Jul 19 |
| Zucchini & Summer Squash | Apr 25 – May 2 | — | May 30 – Jun 13 | Jul 12 – Jul 26 |
| Winter Squash & Pumpkins | Apr 25 – May 2 | — | May 30 – Jun 13 | — |
| Melons & Watermelon | Apr 25 – May 2 | Jun 6 – Jun 20 | — | — |
| Carrots | — | — | May 2 – May 30 | Jun 28 – Jul 12 |
| Beets | — | — | May 2 – May 30 | Jul 12 – Jul 26 |
| Potatoes | — | — | May 2 – May 23 | — |
| Swiss Chard | — | — | May 9 – Jun 6 | Jul 12 – Jul 26 |
| Cilantro | — | — | May 9 – May 30 | Jul 26 – Aug 16 |
| Green Beans | — | — | May 30 – Jun 20 | Jul 5 – Jul 19 |
| Sweet Corn | — | — | May 30 – Jun 13 | — |
| Sweet Potatoes | — | Jun 6 – Jun 27 | — | — |
| Garlic | — | — | — | Sep 6 – Oct 11 |
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 Devils Twr #2, WY weather station, 21 km away (elevation 3,862 ft (1,177 m)).
Frost dates near Moorcroft
- Devils Tower May 23 · Sep 20
- Rozet May 15 · Oct 1
- Sundance May 21 · Sep 25
- Hulett May 17 · Sep 23
- Upton May 20 · Sep 23
- Alva May 17 · Sep 23
- Gillette May 15 · Oct 1
- Osage May 20 · Sep 23
- Weston May 23 · Sep 18
- Beulah May 17 · Sep 27
Frequently asked questions
When is the last frost in Moorcroft, WY?
The median last spring frost in Moorcroft, WY is May 23. There is still about a 10% chance of frost after June 6, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Moorcroft, WY?
The median first fall frost is September 20, with about a 10% chance of frost before September 4.
How long is the growing season in Moorcroft, WY?
About 120 days between the median last spring frost and first fall frost.
What planting zone is Moorcroft, WY?
Moorcroft, WY is in USDA hardiness zone 4b.