Wyoming Frost Dates
Across Wyoming's 99 cities and towns, the average last spring frost runs from April 28 in Basin to June 20 in Jackson. Average last frost elsewhere: Cheyenne May 14 and Casper May 10. In 11 towns, frost is possible in any month.
Frost dates for every city and town in Wyoming
Dates are for 32°F at the NOAA station nearest the ZIP code at each Wyoming town's center. "Safer date" is when only 1 year in 10 still gets a frost, a good target for tomatoes and peppers.
| City | Average last frost | Safer date | Average first frost | Frost-free days |
|---|---|---|---|---|
| Afton | Jun 20 | Jul 7 | Sep 1 | 73 |
| Albin | May 14 | May 25 | Oct 2 | 141 |
| Alpine | Frost possible any month | |||
| Baggs | Jun 1 | Jun 18 | Sep 18 | 109 |
| Bairoil | May 21 | Jun 10 | Sep 27 | 129 |
| Bar Nunn | May 10 | May 24 | Sep 29 | 142 |
| Basin | Apr 28 | May 11 | Oct 10 | 165 |
| Bear River | Jun 14 | Jul 1 | Sep 9 | 87 |
| Big Piney | Frost possible any month | |||
| Buffalo | May 24 | Jun 9 | Sep 21 | 120 |
| Burlington | May 12 | May 27 | Sep 28 | 139 |
| Burns | May 14 | May 27 | Sep 26 | 135 |
| Byron | May 6 | May 20 | Oct 1 | 148 |
| Casper | May 10 | May 24 | Sep 29 | 142 |
| Cheyenne | May 14 | May 28 | Oct 1 | 140 |
| Chugwater | May 18 | Jun 2 | Sep 24 | 129 |
| Clearmont | May 14 | May 29 | Sep 30 | 139 |
| Cody | May 15 | Jun 1 | Sep 25 | 133 |
| Cokeville | May 19 | Jun 5 | Sep 21 | 125 |
| Cowley | May 9 | May 25 | Sep 29 | 143 |
| Dayton | May 24 | Jun 7 | Sep 18 | 117 |
| Deaver | May 6 | May 20 | Oct 1 | 148 |
| Diamondville | Frost possible any month | |||
| Dixon | Jun 1 | Jun 18 | Sep 18 | 109 |
| Douglas | May 23 | Jun 7 | Sep 22 | 122 |
| Dubois | Frost possible any month | |||
| East Thermopolis | May 24 | Jun 9 | Sep 16 | 115 |
| Edgerton | May 22 | Jun 6 | Sep 22 | 123 |
| Elk Mountain | May 28 | Jun 13 | Sep 13 | 108 |
| Encampment | Jun 2 | Jun 21 | Sep 12 | 102 |
| Evanston | Jun 14 | Jul 1 | Sep 9 | 87 |
| Evansville | May 12 | May 26 | Oct 1 | 142 |
| Fort Laramie | May 7 | May 24 | Oct 3 | 149 |
| Frannie | May 6 | May 20 | Oct 1 | 148 |
| Gillette | May 15 | May 27 | Oct 1 | 139 |
| Glendo | May 9 | May 24 | Oct 5 | 149 |
| Glenrock | May 12 | May 26 | Oct 1 | 142 |
| Granger | May 25 | Jun 11 | Sep 27 | 125 |
| Green River | May 24 | Jun 10 | Sep 22 | 121 |
| Greybull | Apr 28 | May 11 | Oct 10 | 165 |
| Guernsey | May 7 | May 21 | Oct 6 | 152 |
| Hanna | Jun 12 | Jun 30 | Sep 7 | 87 |
| Hartville | May 11 | May 25 | Oct 3 | 145 |
| Hudson | May 18 | Jun 3 | Sep 27 | 132 |
| Hulett | May 17 | May 30 | Sep 23 | 129 |
| Jackson | Jun 20 | Jul 9 | Aug 31 | 72 |
| Kaycee | May 18 | May 31 | Sep 25 | 130 |
| Kemmerer | Frost possible any month | |||
| Kirby | May 24 | Jun 9 | Sep 16 | 115 |
| La Barge | Jun 9 | Jun 27 | Sep 4 | 87 |
| LaGrange | May 14 | May 29 | Oct 1 | 140 |
| Lander | May 13 | Jun 1 | Oct 2 | 142 |
| Laramie | Jun 7 | Jun 29 | Sep 4 | 89 |
| Lingle | May 20 | Jun 7 | Sep 22 | 125 |
| Lost Springs | May 19 | Jun 2 | Sep 23 | 127 |
| Lovell | May 9 | May 25 | Sep 29 | 143 |
| Lusk | May 23 | Jun 8 | Sep 20 | 120 |
| Lyman | Jun 14 | Jul 1 | Sep 9 | 87 |
| Manderson | May 4 | May 18 | Oct 1 | 150 |
| Manville | May 23 | Jun 8 | Sep 20 | 120 |
| Marbleton | Frost possible any month | |||
| Medicine Bow | Jun 1 | Jun 19 | Sep 8 | 99 |
| Meeteetse | Frost possible any month | |||
| Midwest | May 22 | Jun 6 | Sep 22 | 123 |
| Mills | May 10 | May 24 | Sep 29 | 142 |
| Moorcroft | May 15 | May 27 | Oct 1 | 139 |
| Mountain View | Jun 14 | Jul 1 | Sep 9 | 87 |
| Newcastle | May 13 | May 26 | Oct 3 | 143 |
| Opal | Frost possible any month | |||
| Pavillion | May 21 | Jun 6 | Sep 20 | 122 |
| Pine Bluffs | May 16 | Jun 1 | Sep 27 | 134 |
| Pine Haven | May 23 | Jun 6 | Sep 20 | 120 |
| Pinedale | Frost possible any month | |||
| Powell | May 15 | Jun 1 | Sep 25 | 133 |
| Ranchester | May 24 | Jun 7 | Sep 18 | 117 |
| Rawlins | Jun 1 | Jun 17 | Sep 15 | 106 |
| Riverside | Jun 2 | Jun 21 | Sep 12 | 102 |
| Riverton | May 12 | May 26 | Sep 24 | 135 |
| Rock River | May 28 | Jun 13 | Sep 13 | 108 |
| Rock Springs | May 24 | Jun 9 | Sep 24 | 123 |
| Rolling Hills | May 12 | May 26 | Oct 1 | 142 |
| Saratoga | Jun 2 | Jun 21 | Sep 12 | 102 |
| Sheridan | May 18 | Jun 2 | Sep 24 | 129 |
| Shoshoni | May 7 | May 18 | Oct 3 | 149 |
| Sinclair | Jun 1 | Jun 17 | Sep 15 | 106 |
| Star Valley Ranch | Frost possible any month | |||
| Sundance | May 21 | Jun 5 | Sep 25 | 127 |
| Superior | May 22 | Jun 9 | Sep 28 | 129 |
| Ten Sleep | May 22 | Jun 7 | Sep 18 | 119 |
| Thayne | Frost possible any month | |||
| Thermopolis | May 24 | Jun 9 | Sep 16 | 115 |
| Torrington | May 20 | Jun 7 | Sep 22 | 125 |
| Upton | May 20 | Jun 4 | Sep 23 | 126 |
| Van Tassell | May 17 | May 31 | Sep 28 | 134 |
| Wamsutter | Jun 5 | Jun 23 | Sep 14 | 101 |
| Wheatland | May 19 | Jun 2 | Sep 22 | 126 |
| Worland | May 4 | May 18 | Oct 1 | 150 |
| Wright | May 25 | Jun 8 | Sep 23 | 121 |
| Yoder | May 15 | Jun 2 | Sep 27 | 135 |
Source: NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020. City centers from the US Census Bureau. Click a city for its nearest station and, where it has frost dates, hard-freeze dates and a vegetable planting calendar. See how we calculate.
Frequently asked questions
When is the last frost in Cheyenne, WY?
The average last spring frost in Cheyenne is May 14, and only 1 year in 10 has a frost after May 28. The average first fall frost is October 1. These come from NOAA's 1991–2020 records at the Cheyenne WFO station.
When should I plant tomatoes in Wyoming?
UNH Extension times tomato transplants for 1 to 2 weeks after the average last frost. In Cheyenne that's about May 21 to May 28. Look up your ZIP code for your own dates and a full vegetable planting calendar.
More for Wyoming: Wyoming climate zones (insulation) · Wyoming planting zones · Frost line depth by state