Frost dates
Frost dates in Idaho
Typical last spring frost and first fall frost for 127 weather stations across Idaho, from NOAA’s 1991–2020 climate normals.
Last spring frost
Apr 25 – Jun 10
Typical across Idaho (middle: May 16)
First fall frost
Sep 9 – Oct 16
Typical across Idaho (middle: Sep 29)
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 |
|---|---|---|---|
| Aberdeen Experiment Station | May 21 | Sep 20 | 122 |
| American Falls | May 4 | Oct 8 | 157 |
| American Falls 6 NE | May 14 | Oct 2 | 141 |
| Arco | May 22 | Sep 22 | 123 |
| Arco 17 SW | May 24 | Oct 1 | 130 |
| Arrowrock Dam | Apr 28 | Oct 14 | 169 |
| Ashton 1 N | May 21 | Sep 21 | 123 |
| Bayview Model Basin | May 22 | Sep 22 | 123 |
| Bellevue | May 13 | Oct 2 | 142 |
| Bern | Jun 17 | Sep 3 | 78 |
| Blackfoot Fire Dept | May 5 | Oct 3 | 151 |
| Boise 7 N | May 17 | Oct 12 | 148 |
| Boise Air Terminal | Apr 24 | Oct 21 | 180 |
| Boise Lucky Peak Dam | Apr 30 | Oct 22 | 175 |
| Bonners Ferry | Apr 30 | Oct 4 | 157 |
| Brownlee Dam | Apr 2 | Nov 5 | 217 |
| Bruneau | Apr 17 | Oct 17 | 183 |
| Buhl #2 | Apr 25 | Oct 15 | 173 |
| Burley Municipal Airport | May 7 | Oct 4 | 150 |
| Cabinet Gorge | May 9 | Oct 8 | 152 |
| Cambridge | May 15 | Sep 27 | 135 |
| Cascade 1 NW | May 30 | Sep 19 | 112 |
| Castleford 2 N | May 17 | Sep 29 | 135 |
| Challis Airport | May 14 | Sep 25 | 134 |
| Chilly Barton Flat | Jun 14 | Sep 8 | 86 |
| Coeur D'Alene | Apr 22 | Oct 18 | 179 |
| Cottonwood 2 WSW | May 6 | Oct 13 | 160 |
| Council | May 10 | Oct 2 | 145 |
| Craters Of The Moon | Jun 19 | Sep 9 | 82 |
| Deer Flat Dam | Apr 23 | Oct 18 | 178 |
| Downey | May 31 | Sep 18 | 110 |
| Driggs | Jun 13 | Sep 9 | 88 |
| Dubois Experiment Station | May 18 | Sep 30 | 135 |
| Dworshak Fish Hatchery | Apr 20 | Oct 20 | 183 |
| Elk Rvr | May 16 | Sep 23 | 130 |
| Emmett 2 E | Apr 30 | Oct 17 | 170 |
| Fairfield RS | Jun 8 | Sep 14 | 98 |
| Fenn RS | Apr 26 | Oct 20 | 177 |
| Fort Hall 1 NNE | May 20 | Sep 20 | 123 |
| Garden Valley | Jun 1 | Sep 10 | 101 |
| Gibbonsville #2 | Jun 1 | Sep 17 | 108 |
| Glenns Ferry | May 1 | Oct 3 | 155 |
| Grace | May 29 | Sep 17 | 111 |
| Grand View 4 NW | Apr 28 | Oct 6 | 161 |
| Grangeville | May 9 | Oct 3 | 147 |
| Hagerman 2 SW | May 3 | Oct 1 | 151 |
| Hamer 4 NW | Jun 3 | Sep 11 | 100 |
| Hazelton | May 7 | Oct 5 | 151 |
| Hill City 1 W | Jun 16 | Sep 6 | 82 |
| Homedale 1 SE | Apr 24 | Oct 9 | 168 |
| Howe | May 24 | Sep 14 | 113 |
| Idaho City | Jun 17 | Sep 5 | 80 |
| Idaho Falls - Kifi | May 9 | Oct 1 | 145 |
| Idaho Falls 16 SE | Jun 9 | Sep 11 | 94 |
| Idaho Falls 46 W | Jun 11 | Sep 6 | 87 |
| Idaho Falls Fanning Field | May 23 | Sep 20 | 120 |
| Jerome | May 2 | Oct 14 | 165 |
| Jerome County Airport | May 1 | Oct 14 | 166 |
| Kamiah | Apr 29 | Oct 5 | 159 |
| Kellogg | May 14 | Sep 26 | 135 |
| Kooskia 5 SSE | Apr 30 | Oct 11 | 164 |
| Lava Hot Springs | May 21 | Sep 21 | 123 |
| Lewiston Nez Perce County Airport | Apr 6 | Oct 26 | 203 |
| Lifton Pumping Station | May 19 | Sep 21 | 125 |
| Lowell Three Rivers | Apr 16 | Oct 25 | 192 |
| Lowman | Jun 6 | Sep 4 | 90 |
| Mackay Lost Rvr RS | Jun 1 | Sep 20 | 111 |
| Malad City | May 22 | Sep 20 | 121 |
| Malta | Jun 5 | Sep 13 | 100 |
| Malta 4 ESE | Jun 1 | Sep 19 | 110 |
| Massacre Rocks Sp | May 20 | Sep 26 | 129 |
| May 2 SSE | Jun 12 | Sep 6 | 86 |
| Mccall | Jun 22 | Sep 2 | 72 |
| Mccall Airport | Jun 10 | Sep 10 | 92 |
| Mccammon | May 23 | Sep 24 | 124 |
| Middle Fork Lodge | May 21 | Sep 18 | 120 |
| Minidoka Dam | May 16 | Oct 1 | 138 |
| Monteview | Jun 12 | Sep 7 | 87 |
| Mountain Home | May 2 | Oct 8 | 159 |
| Mullan | May 12 | Sep 30 | 141 |
| Mullan Pass Vor/Dme | Jun 10 | Sep 23 | 105 |
| Murphy 10 W | May 17 | Sep 30 | 136 |
| Nampa Sugar Factory | Apr 29 | Oct 13 | 167 |
| Nezperce | May 24 | Sep 20 | 119 |
| Oakley | May 15 | Oct 2 | 140 |
| Ola | May 31 | Sep 16 | 108 |
| Parma Experiment Station | Apr 27 | Oct 9 | 165 |
| Paul 1 ENE | May 6 | Oct 6 | 153 |
| Payette | Apr 19 | Oct 20 | 184 |
| Picabo | Jun 16 | Sep 9 | 85 |
| Pierce | Jun 3 | Sep 7 | 96 |
| Plummer 3 WSW | May 11 | Oct 5 | 147 |
| Pocatello 2 NE | May 16 | Oct 2 | 139 |
| Pocatello City | May 2 | Oct 11 | 162 |
| Pocatello Regional Airport | May 23 | Sep 18 | 118 |
| Porthill 1 SW | May 4 | Sep 30 | 149 |
| Potlatch 3 NNE | May 15 | Sep 21 | 129 |
| Powell | May 31 | Sep 12 | 104 |
| Preston | May 16 | Sep 28 | 135 |
| Prichard 3 ESE | May 31 | Sep 5 | 97 |
| Priest Rvr Experiment Station | May 20 | Sep 13 | 116 |
| Rexburg Byu Idaho | May 12 | Sep 24 | 135 |
| Rexburg Madison County Airport | May 15 | Sep 23 | 131 |
| Reynolds | May 21 | Sep 28 | 130 |
| Richfield | May 24 | Sep 26 | 125 |
| Rigby | May 9 | Oct 5 | 149 |
| Riggins | May 6 | Oct 9 | 156 |
| Saint Anthony | May 17 | Sep 22 | 128 |
| Saint Maries | May 3 | Oct 4 | 154 |
| Salmon-Ksra | May 17 | Sep 24 | 130 |
| Sandpoint Experiment Station | May 8 | Sep 28 | 143 |
| Shoshone 1 WNW | Apr 24 | Oct 16 | 175 |
| Shoup | May 3 | Oct 8 | 158 |
| Silver City 5 W | May 31 | Oct 6 | 128 |
| Small 6 N | Jun 5 | Sep 20 | 107 |
| Sugar City | May 29 | Sep 13 | 107 |
| Swan Falls Ph | Apr 12 | Oct 26 | 197 |
| Taylor Rch | May 11 | Sep 30 | 142 |
| Tetonia Experiment Station | Jun 15 | Sep 7 | 84 |
| Twin Falls 6 E | May 6 | Oct 3 | 150 |
| Twin Falls Sun Vly Regional Airport | May 9 | Oct 4 | 148 |
| Twin Falls-Kmvt | Apr 30 | Oct 9 | 162 |
| Wallace | May 5 | Oct 2 | 150 |
| Weiser | Apr 23 | Oct 13 | 173 |
| Winchester | May 23 | Sep 25 | 125 |
| Yellowpine | Jun 12 | Sep 11 | 91 |
| Yellowpine Bar | May 2 | Oct 10 | 161 |
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.