Wyoming frost dates
Across 126 weather stations in Wyoming, the median last spring frost runs from Apr 28 in Basin to Jun 24 in Moose 1 mi NNE, and the first fall frost from Aug 28 to Oct 10.
Wyoming at a glance
- Weather stations
- 126
- Earliest last frost
- Apr 28 Basin
- Latest last frost
- Jun 24 Moose 1 mi NNE
- Longest season
- 164 days Basin
- Typical season
- about 125 frost-free days
- Hardiness zones
- Zones 4a to 5b
Frost dates by weather station
| Weather station | Last spring frost | First fall frost | Frost-free days | Zone |
|---|---|---|---|---|
| Afton | Jun 20 | Sep 1 | 71 | 5b |
| Albin | May 14 | Oct 2 | 142 | 5b |
| Alta | Jun 14 | Sep 11 | 85 | 5a |
| Archer | May 21 | Sep 24 | 124 | 5b |
| Baggs | Jun 1 | Sep 18 | 108 | 4b |
| Basin | Apr 28 | Oct 10 | 164 | 4b |
| Bates Creek | May 22 | Sep 26 | 125 | 5a |
| Big Horn | May 17 | Sep 28 | 132 | 5a |
| Billy Creek | May 19 | Sep 21 | 123 | 5a |
| Bitter Creek | Jun 1 | Sep 16 | 106 | 5a |
| Black Mountain | May 14 | Oct 3 | 140 | 4b |
| Boysen Dam | May 5 | Oct 7 | 153 | 4b |
| Buckboard Marina | May 24 | Sep 23 | 118 | 5b |
| Buffalo | May 24 | Sep 21 | 118 | 5a |
| Buffalo Bill Dam | May 17 | Oct 3 | 136 | 5a |
| Buffalo Johnson County Airport | May 13 | Oct 1 | 141 | 5a |
| Burris | Jun 1 | Sep 14 | 104 | 5a |
| Carpenter | May 14 | Sep 26 | 133 | 5b |
| Casper | May 12 | Oct 1 | 143 | 5a |
| Casper Natrona County Airport | May 26 | Sep 22 | 117 | 5a |
| Casper Wastewater Plant | May 10 | Sep 29 | 138 | 5a |
| Centennial | Jun 2 | Sep 19 | 106 | 5a |
| Cheyenne | May 12 | Oct 1 | 141 | 5b |
| Chugwater | May 18 | Sep 24 | 129 | 5a |
| Church Buttes Gas Plant | May 25 | Sep 27 | 124 | 5a |
| Clark | May 18 | Sep 22 | 125 | 5a |
| Clearmont | May 24 | Sep 16 | 114 | 5a |
| Cody | May 12 | Oct 1 | 140 | 5a |
| Cody 12 mi SE | May 24 | Sep 15 | 114 | 5a |
| Cody 21 mi SW | May 29 | Sep 18 | 110 | 5a |
| Colony | May 7 | Oct 3 | 149 | 4b |
| Dayton | May 24 | Sep 18 | 114 | 5a |
| Deaver | May 6 | Oct 1 | 148 | 5a |
| Devils Tower | May 23 | Sep 20 | 118 | 4b |
| Dillinger | May 25 | Sep 17 | 113 | 4b |
| Diversion Dam | May 21 | Sep 20 | 119 | 5a |
| Double Four Ranch | Jun 2 | Sep 9 | 99 | 5a |
| Douglas | May 19 | Sep 23 | 126 | 5a |
| Douglas Converse County Airport | May 23 | Sep 22 | 122 | 5a |
| Dull Center | May 15 | Sep 27 | 133 | 4b |
| Echeta | May 21 | Sep 23 | 123 | 5a |
| Elk Mountain | May 28 | Sep 13 | 108 | 5a |
| Emblem | May 12 | Sep 28 | 136 | 5a |
| Evanston | Jun 12 | Sep 12 | 90 | 5a |
| Evanston Burns Field | Jun 3 | Sep 25 | 113 | 5a |
| Gillette | May 15 | Oct 1 | 136 | 4b |
| Gillette Campbell Airport | May 22 | Sep 25 | 125 | 5a |
| Glendo | May 25 | Sep 15 | 112 | 5a |
| Glendo Reservoir USBR | May 9 | Oct 5 | 148 | 5a |
| Green River | May 24 | Sep 22 | 120 | 5a |
| Greybull | May 11 | Sep 23 | 133 | 4b |
| Greybull S Big Horn Airport | May 4 | Oct 1 | 149 | 4b |
| Guernsey | May 7 | Oct 6 | 152 | 5a |
| Guernsey Dam | May 11 | Oct 3 | 144 | 5a |
| Heart Mountain | May 15 | Sep 25 | 132 | 5a |
| Hecla | May 27 | Sep 19 | 115 | 5b |
| Hulett | May 17 | Sep 23 | 128 | 5a |
| Jeffrey City | Jun 1 | Sep 13 | 104 | 4b |
| Kaycee | May 18 | Sep 25 | 129 | 5a |
| La Barge | Jun 9 | Sep 4 | 84 | 4a |
| La Grange | May 14 | Oct 1 | 137 | 5a |
| Lance Creek | May 17 | Sep 25 | 129 | 4b |
| Lander | May 13 | Oct 2 | 140 | 5a |
| Lander Hunt Field Airport | May 18 | Sep 27 | 131 | 5a |
| Laramie 2 mi NW | Jun 7 | Sep 4 | 88 | 4a |
| Laramie 4 mi SE | May 22 | Sep 28 | 126 | 5b |
| Laramie Regional Airport | Jun 2 | Sep 15 | 102 | 4a |
| Leiter | May 14 | Sep 30 | 137 | 5a |
| Leo | May 20 | Sep 28 | 128 | 5a |
| Lingle | May 20 | Sep 22 | 122 | 5a |
| Lovell | May 9 | Sep 29 | 142 | 5a |
| Lusk 2 mi SW | May 23 | Sep 20 | 119 | 5a |
| Lusk 25 mi NE | May 14 | Oct 1 | 139 | 5a |
| Medicine Bow | Jun 1 | Sep 8 | 97 | 4a |
| Midwest | May 22 | Sep 22 | 121 | 5a |
| Moorcroft | May 22 | Sep 28 | 127 | 4b |
| Moose | Jun 20 | Aug 31 | 70 | 4a |
| Moose 1 mi NNE | Jun 24 | Aug 28 | 63 | 4a |
| Mountain View | Jun 14 | Sep 9 | 84 | 5b |
| Muddy Gap | May 21 | Sep 27 | 126 | 5b |
| Newcastle | May 13 | Oct 3 | 143 | 4b |
| Old Fort Laramie | May 14 | Sep 26 | 134 | 5a |
| Pathfinder Dam | May 9 | Oct 7 | 148 | 5a |
| Pavillion | May 14 | Sep 30 | 139 | 5a |
| Phillips | May 21 | Sep 21 | 121 | 5a |
| Pine Bluffs 1 mi ESE | May 10 | Oct 1 | 142 | 5a |
| Pine Bluffs 5 mi W | May 16 | Sep 27 | 132 | 5a |
| Powder River | May 23 | Sep 20 | 121 | 5a |
| Powder River (school) | May 30 | Sep 22 | 115 | 5a |
| Powell Field Station | May 19 | Sep 20 | 123 | 5a |
| Rawlins | May 17 | Oct 2 | 138 | 5a |
| Rawlins Municipal Airport | Jun 1 | Sep 15 | 105 | 5a |
| Redbird | May 16 | Sep 24 | 130 | 4b |
| Riverton | May 16 | Sep 28 | 133 | 5a |
| Rochelle | May 25 | Sep 14 | 110 | 4b |
| Rock Springs Airport | May 22 | Sep 28 | 126 | 5a |
| Rock Springs Fire Department | May 24 | Sep 24 | 121 | 5a |
| Saratoga | Jun 2 | Sep 12 | 101 | 5a |
| Saratoga 4 mi N | Jun 12 | Sep 7 | 83 | 5a |
| Seminoe Reservoir USBR | May 12 | Oct 4 | 143 | 5a |
| Shell | May 16 | Sep 24 | 130 | 5a |
| Sheridan County Airport | May 21 | Sep 23 | 123 | 5a |
| Sheridan Field Station | May 18 | Sep 24 | 127 | 5a |
| Shoshoni | May 7 | Oct 3 | 145 | 4b |
| Story | May 24 | Sep 23 | 120 | 5a |
| Sundance | May 21 | Sep 25 | 124 | 4b |
| Sundance 8 mi NNW | May 23 | Sep 24 | 121 | 4b |
| Sybille Research Unit | May 22 | Sep 24 | 125 | 4a |
| Tensleep 16 mi SSE | May 22 | Sep 18 | 117 | 5a |
| Tensleep 4 mi NE | May 10 | Oct 1 | 141 | 5a |
| Thermopolis | May 5 | Oct 5 | 152 | 4b |
| Thermopolis 21 mi WNW | May 29 | Sep 17 | 110 | 5a |
| Thermopolis 9 mi NE | May 24 | Sep 16 | 112 | 4b |
| Torrington | May 17 | Sep 28 | 133 | 5a |
| Torrington Experiment Farm | May 14 | Sep 24 | 130 | 5a |
| Torrington Municipal Airport | May 11 | Sep 29 | 139 | 5a |
| Upton | May 20 | Sep 23 | 123 | 4b |
| Wamsutter | Jun 5 | Sep 14 | 101 | 4b |
| Wapiti | May 27 | Sep 25 | 121 | 5a |
| Weston | May 23 | Sep 18 | 118 | 4b |
| Whalen Dam USBR | May 7 | Oct 3 | 146 | 5a |
| Wheatland | May 19 | Sep 22 | 125 | 5a |
| Worland | May 13 | Sep 26 | 133 | 4b |
| Wright | May 25 | Sep 23 | 120 | 5a |
| Yellowstone Park Mammoth | Jun 3 | Sep 14 | 102 | 4b |
| Yoder | May 15 | Sep 27 | 132 | 5a |
Median dates from NOAA 1991–2020 climate normals. How to read them.