Frost dates
Frost dates in Wyoming
Typical last spring frost and first fall frost for 129 weather stations across Wyoming, from NOAA’s 1991–2020 climate normals.
Last spring frost
May 10 – Jun 2
Typical across Wyoming (middle: May 20)
First fall frost
Sep 13 – Oct 3
Typical across Wyoming (middle: Sep 24)
Your own yard can differ by weeks from the nearest town. Get frost dates for your exact spot →
By town
| Station | Last spring frost | First fall frost | Frost-free days |
|---|---|---|---|
| Afton | Jun 20 | Sep 1 | 73 |
| Albin | May 14 | Oct 2 | 141 |
| Alta 1 NNW | Jun 14 | Sep 11 | 89 |
| Archer | May 21 | Sep 24 | 126 |
| Baggs | Jun 1 | Sep 18 | 109 |
| Basin | Apr 28 | Oct 10 | 165 |
| Bates Creek #2 | May 22 | Sep 26 | 127 |
| Big Horn | May 17 | Sep 28 | 134 |
| Billy Creek | May 19 | Sep 21 | 125 |
| Bitter Creek 4 NE | Jun 1 | Sep 16 | 107 |
| Black Mountain | May 14 | Oct 3 | 142 |
| Boysen Dam | May 5 | Oct 7 | 155 |
| Buckboard Marina | May 24 | Sep 23 | 122 |
| Buffalo | May 24 | Sep 21 | 120 |
| Buffalo Bill Dam | May 17 | Oct 3 | 139 |
| Buffalo Johnson County Airport | May 13 | Oct 1 | 141 |
| Burris | Jun 1 | Sep 14 | 105 |
| Carpenter 3 N | May 14 | Sep 26 | 135 |
| Casper 1 SW | May 12 | Oct 1 | 142 |
| Casper Natrona County Airport | May 26 | Sep 22 | 119 |
| Casper Water Plant | May 10 | Sep 29 | 142 |
| Centennial 1 NE | Jun 2 | Sep 19 | 109 |
| Cheyenne | May 12 | Oct 1 | 142 |
| Cheyenne | May 14 | Oct 1 | 140 |
| Chugwater | May 18 | Sep 24 | 129 |
| Church Buttes Gas Plt | May 25 | Sep 27 | 125 |
| Clark 3 NE | May 18 | Sep 22 | 127 |
| Clearmont 5 SW | May 24 | Sep 16 | 115 |
| Cody | May 12 | Oct 1 | 142 |
| Cody 12 SE | May 24 | Sep 15 | 114 |
| Cody 21 SW | May 29 | Sep 18 | 112 |
| Colony | May 7 | Oct 3 | 149 |
| Dayton | May 24 | Sep 18 | 117 |
| Deaver | May 6 | Oct 1 | 148 |
| Devils Twr #2 | May 23 | Sep 20 | 120 |
| Dillinger | May 25 | Sep 17 | 115 |
| Diversion Dam | May 21 | Sep 20 | 122 |
| Double Four Rch | Jun 2 | Sep 9 | 99 |
| Douglas 1 SE | May 19 | Sep 23 | 127 |
| Douglas Converse County Airport | May 23 | Sep 22 | 122 |
| Dull Ctr 1 SE | May 15 | Sep 27 | 135 |
| Echeta 2 NW | May 21 | Sep 23 | 125 |
| Elk Mountain | May 28 | Sep 13 | 108 |
| Emblem | May 12 | Sep 28 | 139 |
| Evanston 1 E | Jun 12 | Sep 12 | 92 |
| Evanston Burns Field | Jun 3 | Sep 25 | 114 |
| Gillette 4 SE | May 15 | Oct 1 | 139 |
| Gillette Campbell Airport | May 22 | Sep 25 | 126 |
| Glendo 6 NE | May 25 | Sep 15 | 113 |
| Glendo Reservoir Usbr | May 9 | Oct 5 | 149 |
| Green Rvr | May 24 | Sep 22 | 121 |
| Greybull | May 11 | Sep 23 | 135 |
| Greybull S Big Horn Airport | May 4 | Oct 1 | 150 |
| Guernsey 2 NW | May 7 | Oct 6 | 152 |
| Guernsey Dam #2 | May 11 | Oct 3 | 145 |
| Heart Mountain | May 15 | Sep 25 | 133 |
| Hecla 1 E | May 27 | Sep 19 | 115 |
| Hulett | May 17 | Sep 23 | 129 |
| Jeffrey City | Jun 1 | Sep 13 | 104 |
| Kaycee | May 18 | Sep 25 | 130 |
| La Barge | Jun 9 | Sep 4 | 87 |
| La Grange | May 14 | Oct 1 | 140 |
| Lance Creek 11 NNE | May 17 | Sep 25 | 131 |
| Lander 11 SSE | May 13 | Oct 2 | 142 |
| Lander Hunt Field Airport | May 18 | Sep 27 | 132 |
| Laramie 2 NW | Jun 7 | Sep 4 | 89 |
| Laramie 4 SE | May 22 | Sep 28 | 129 |
| Laramie Regional Airport | Jun 2 | Sep 15 | 105 |
| Leiter 9 N | May 14 | Sep 30 | 139 |
| Leo 6 SW | May 20 | Sep 28 | 131 |
| Lingle 2 WSW | May 20 | Sep 22 | 125 |
| Lovell | May 9 | Sep 29 | 143 |
| Lusk 2 SW | May 23 | Sep 20 | 120 |
| Lusk 25 NE | May 14 | Oct 1 | 140 |
| Medicine Bow | Jun 1 | Sep 8 | 99 |
| Midwest | May 22 | Sep 22 | 123 |
| Moorcroft 3 S | May 22 | Sep 28 | 129 |
| Moose | Jun 20 | Aug 31 | 72 |
| Moose 1 NNE | Jun 24 | Aug 28 | 65 |
| Mountain View | Jun 14 | Sep 9 | 87 |
| Muddy Gap | May 21 | Sep 27 | 129 |
| Newcastle | May 13 | Oct 3 | 143 |
| Old Fort Laramie | May 14 | Sep 26 | 135 |
| Pathfinder Dam | May 9 | Oct 7 | 151 |
| Pavillion | May 14 | Sep 30 | 139 |
| Phillips | May 21 | Sep 21 | 123 |
| Pine Bluffs 1 ESE | May 10 | Oct 1 | 144 |
| Pine Bluffs 5 W | May 16 | Sep 27 | 134 |
| Powder River #2 | May 23 | Sep 20 | 120 |
| Powder Rvr (School) | May 30 | Sep 22 | 115 |
| Powell Field Station | May 19 | Sep 20 | 124 |
| Rawlins 1 N | May 17 | Oct 2 | 138 |
| Rawlins Municipal Airport | Jun 1 | Sep 15 | 106 |
| Redbird | May 16 | Sep 24 | 131 |
| Riverton | May 12 | Sep 24 | 135 |
| Riverton | May 16 | Sep 28 | 135 |
| Rochelle 7 ENE | May 25 | Sep 14 | 112 |
| Rock Springs Airport | May 22 | Sep 28 | 129 |
| Rock Springs Fire Dept | May 24 | Sep 24 | 123 |
| Saratoga | Jun 2 | Sep 12 | 102 |
| Saratoga 4 N | Jun 12 | Sep 7 | 87 |
| Seminoe Reservoir Usbr | May 12 | Oct 4 | 145 |
| Shell | May 16 | Sep 24 | 131 |
| Sheridan County Airport | May 21 | Sep 23 | 125 |
| Sheridan Field Station | May 18 | Sep 24 | 129 |
| Shoshoni | May 7 | Oct 3 | 149 |
| Story | May 24 | Sep 23 | 122 |
| Sundance | May 21 | Sep 25 | 127 |
| Sundance 8 NNW | May 23 | Sep 24 | 124 |
| Sybille Rsch Unit | May 22 | Sep 24 | 125 |
| Tensleep 16 SSE | May 22 | Sep 18 | 119 |
| Tensleep 4 NE | May 10 | Oct 1 | 144 |
| Thermopolis | May 5 | Oct 5 | 153 |
| Thermopolis 21 WNW | May 29 | Sep 17 | 111 |
| Thermopolis 9 NE | May 24 | Sep 16 | 115 |
| Torrington 29 N | May 17 | Sep 28 | 134 |
| Torrington Experiment Farm | May 14 | Sep 24 | 133 |
| Torrington Municipal Airport | May 11 | Sep 29 | 141 |
| Upton | May 20 | Sep 23 | 126 |
| Wamsutter | Jun 5 | Sep 14 | 101 |
| Wapiti 1 WSW | May 27 | Sep 25 | 121 |
| Weston 1 E | May 23 | Sep 18 | 118 |
| Whalen Dam Usbr | May 7 | Oct 3 | 149 |
| Wheatland 4 N | May 19 | Sep 22 | 126 |
| Worland | May 4 | Oct 1 | 150 |
| Worland | May 13 | Sep 26 | 136 |
| Wright 12 W | May 25 | Sep 23 | 121 |
| Yellowstone Park Mammoth | Jun 3 | Sep 14 | 103 |
| Yoder 5 W | May 15 | Sep 27 | 135 |
Each date is the median: in half of years the frost comes earlier, in half later. Frost here means a low of 32°F or colder at the station. Low spots and valleys often frost a week or two earlier than these dates; hillsides and city centers later.
Source: NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020. The Field almanac also shows how often frost comes early or late, and a reanalysis reading for your exact location.