Last frost dates in Idaho
127 NOAA weather stations in Idaho have thirty years of frost records. The median station sees its last 32 °F night around May 16; across the state that ranges from Apr 2 to Jun 22, so pick the station nearest you rather than a state-wide figure.
| Plan sowing from this date | ||||||
|---|---|---|---|---|---|---|
| BROWNLEE DAM | Apr 2 | Apr 20 | Mar 15 | Nov 5 | 216 | Plan sowing from this date → |
| LEWISTON NEZ PERCE CO AP | Apr 6 | Apr 26 | Mar 20 | Oct 26 | 200 | Plan sowing from this date → |
| SWAN FALLS PH | Apr 12 | May 6 | Mar 23 | Oct 26 | 193 | Plan sowing from this date → |
| LOWELL THREE RIVERS | Apr 16 | May 4 | Mar 26 | Oct 25 | 191 | Plan sowing from this date → |
| BRUNEAU | Apr 17 | May 7 | Mar 31 | Oct 17 | 181 | Plan sowing from this date → |
| PAYETTE | Apr 19 | May 5 | Apr 1 | Oct 20 | 183 | Plan sowing from this date → |
| DWORSHAK FISH HATCHERY | Apr 20 | May 5 | Apr 1 | Oct 20 | 182 | Plan sowing from this date → |
| COEUR D'ALENE | Apr 22 | May 6 | Apr 4 | Oct 18 | 179 | Plan sowing from this date → |
| DEER FLAT DAM | Apr 23 | May 9 | Apr 5 | Oct 18 | 178 | Plan sowing from this date → |
| WEISER | Apr 23 | May 10 | Apr 3 | Oct 13 | 174 | Plan sowing from this date → |
| BOISE AIR TERMINAL | Apr 24 | May 9 | Apr 4 | Oct 21 | 179 | Plan sowing from this date → |
| HOMEDALE 1 SE | Apr 24 | May 5 | Apr 9 | Oct 9 | 169 | Plan sowing from this date → |
| SHOSHONE 1 WNW | Apr 24 | May 12 | Apr 9 | Oct 16 | 173 | Plan sowing from this date → |
| BUHL #2 | Apr 25 | May 10 | Apr 8 | Oct 15 | 172 | Plan sowing from this date → |
| FENN RS | Apr 26 | May 9 | Apr 8 | Oct 20 | 176 | Plan sowing from this date → |
| PARMA EXP STN | Apr 27 | May 9 | Apr 13 | Oct 9 | 165 | Plan sowing from this date → |
| ARROWROCK DAM | Apr 28 | May 16 | Apr 11 | Oct 14 | 169 | Plan sowing from this date → |
| GRAND VIEW 4 NW | Apr 28 | May 13 | Apr 12 | Oct 6 | 162 | Plan sowing from this date → |
| KAMIAH | Apr 29 | May 12 | Apr 9 | Oct 5 | 163 | Plan sowing from this date → |
| NAMPA SUGAR FACTORY | Apr 29 | May 18 | Apr 15 | Oct 13 | 164 | Plan sowing from this date → |
| BOISE LUCKY PEAK DAM | Apr 30 | May 18 | Apr 11 | Oct 22 | 173 | Plan sowing from this date → |
| BONNERS FERRY | Apr 30 | May 16 | Apr 16 | Oct 4 | 154 | Plan sowing from this date → |
| EMMETT 2 E | Apr 30 | May 17 | Apr 17 | Oct 17 | 168 | Plan sowing from this date → |
| KOOSKIA 5 SSE | Apr 30 | May 13 | Apr 14 | Oct 11 | 162 | Plan sowing from this date → |
| TWIN FALLS-KMVT | Apr 30 | May 14 | Apr 17 | Oct 9 | 161 | Plan sowing from this date → |
| GLENNS FERRY | May 1 | May 16 | Apr 14 | Oct 3 | 154 | Plan sowing from this date → |
| JEROME CO AP | May 1 | May 16 | Apr 17 | Oct 14 | 165 | Plan sowing from this date → |
| JEROME | May 2 | May 30 | Apr 15 | Oct 14 | 166 | Plan sowing from this date → |
| MTN HOME | May 2 | May 23 | Apr 18 | Oct 8 | 157 | Plan sowing from this date → |
| POCATELLO CITY | May 2 | May 18 | Apr 17 | Oct 11 | 161 | Plan sowing from this date → |
| YELLOWPINE BAR | May 2 | May 14 | Apr 18 | Oct 10 | 159 | Plan sowing from this date → |
| HAGERMAN 2 SW | May 3 | May 17 | Apr 19 | Oct 1 | 151 | Plan sowing from this date → |
| SAINT MARIES | May 3 | May 18 | Apr 20 | Oct 4 | 152 | Plan sowing from this date → |
| SHOUP | May 3 | May 21 | Apr 17 | Oct 8 | 157 | Plan sowing from this date → |
| AMERICAN FALLS | May 4 | May 21 | Apr 20 | Oct 8 | 155 | Plan sowing from this date → |
| PORTHILL 1 SW | May 4 | May 28 | Apr 20 | Sep 30 | 145 | Plan sowing from this date → |
| BLACKFOOT FIRE DEPT | May 5 | May 22 | Apr 23 | Oct 3 | 149 | Plan sowing from this date → |
| WALLACE | May 5 | May 21 | Apr 22 | Oct 2 | 149 | Plan sowing from this date → |
| COTTONWOOD 2 WSW | May 6 | May 26 | Apr 22 | Oct 13 | 156 | Plan sowing from this date → |
| PAUL 1ENE | May 6 | May 22 | Apr 23 | Oct 6 | 151 | Plan sowing from this date → |
| RIGGINS | May 6 | May 26 | Apr 23 | Oct 9 | 155 | Plan sowing from this date → |
| TWIN FALLS 6 E | May 6 | May 26 | Apr 22 | Oct 3 | 150 | Plan sowing from this date → |
| BURLEY MUNI AP | May 7 | May 23 | Apr 23 | Oct 4 | 150 | Plan sowing from this date → |
| HAZELTON | May 7 | May 26 | Apr 24 | Oct 5 | 149 | Plan sowing from this date → |
| SANDPOINT EXP STN | May 8 | May 25 | Apr 23 | Sep 28 | 141 | Plan sowing from this date → |
| CABINET GORGE | May 9 | May 25 | Apr 24 | Oct 8 | 153 | Plan sowing from this date → |
| GRANGEVILLE | May 9 | May 27 | Apr 24 | Oct 3 | 146 | Plan sowing from this date → |
| IDAHO FALLS - KIFI | May 9 | Jun 2 | Apr 27 | Oct 1 | 142 | Plan sowing from this date → |
| RIGBY | May 9 | May 25 | Apr 27 | Oct 5 | 148 | Plan sowing from this date → |
| TWIN FALLS SUN VLY RGNL AP | May 9 | May 28 | Apr 25 | Oct 4 | 147 | Plan sowing from this date → |
| COUNCIL | May 10 | Jun 1 | Apr 25 | Oct 2 | 145 | Plan sowing from this date → |
| PLUMMER 3 WSW | May 11 | Jun 4 | Apr 25 | Oct 5 | 143 | Plan sowing from this date → |
| TAYLOR RCH | May 11 | Jun 1 | Apr 29 | Sep 30 | 140 | Plan sowing from this date → |
| MULLAN | May 12 | Jun 19 | Apr 26 | Sep 30 | 138 | Plan sowing from this date → |
| REXBURG BYU IDAHO | May 12 | Jun 2 | Apr 29 | Sep 24 | 132 | Plan sowing from this date → |
| BELLEVUE | May 13 | Jun 3 | Apr 30 | Oct 2 | 139 | Plan sowing from this date → |
| AMERICAN FALLS 6 NE | May 14 | Jun 4 | Apr 30 | Oct 2 | 138 | Plan sowing from this date → |
| CHALLIS AP | May 14 | Jun 2 | May 2 | Sep 25 | 131 | Plan sowing from this date → |
| KELLOGG | May 14 | Jun 3 | Apr 30 | Sep 26 | 131 | Plan sowing from this date → |
| CAMBRIDGE | May 15 | Jun 4 | Apr 29 | Sep 27 | 134 | Plan sowing from this date → |
| OAKLEY | May 15 | Jun 6 | Apr 30 | Oct 2 | 137 | Plan sowing from this date → |
| POTLATCH 3 NNE | May 15 | Jun 2 | Apr 30 | Sep 21 | 126 | Plan sowing from this date → |
| REXBURG MADISON CO AP | May 15 | Jun 3 | May 1 | Sep 23 | 129 | Plan sowing from this date → |
| ELK RVR | May 16 | Jun 1 | May 2 | Sep 23 | 128 | Plan sowing from this date → |
| MINIDOKA DAM | May 16 | Jun 5 | Apr 30 | Oct 1 | 136 | Plan sowing from this date → |
| POCATELLO 2 NE | May 16 | Jun 6 | Apr 30 | Oct 2 | 137 | Plan sowing from this date → |
| PRESTON | May 16 | Jun 4 | May 2 | Sep 28 | 133 | Plan sowing from this date → |
| BOISE 7 N | May 17 | Jun 10 | Apr 27 | Oct 12 | 147 | Plan sowing from this date → |
| CASTLEFORD 2 N | May 17 | Jun 5 | Apr 30 | Sep 29 | 132 | Plan sowing from this date → |
| MURPHY 10 W | May 17 | Jun 6 | May 2 | Sep 30 | 134 | Plan sowing from this date → |
| SAINT ANTHONY | May 17 | Jun 10 | May 4 | Sep 22 | 126 | Plan sowing from this date → |
| SALMON-KSRA | May 17 | Jun 9 | May 3 | Sep 24 | 127 | Plan sowing from this date → |
| DUBOIS EXP STN | May 18 | Jun 9 | May 3 | Sep 30 | 132 | Plan sowing from this date → |
| LIFTON PUMPING STN | May 19 | Jun 5 | May 3 | Sep 21 | 123 | Plan sowing from this date → |
| FT HALL 1 NNE | May 20 | Jun 12 | May 6 | Sep 20 | 119 | Plan sowing from this date → |
| MASSACRE ROCKS SP | May 20 | Jun 9 | May 4 | Sep 26 | 125 | Plan sowing from this date → |
| PRIEST RVR EXP STN | May 20 | Jun 4 | May 6 | Sep 13 | 114 | Plan sowing from this date → |
| ABERDEEN EXP STN | May 21 | Jun 13 | May 4 | Sep 20 | 118 | Plan sowing from this date → |
| ASHTON 1N | May 21 | Jun 13 | May 4 | Sep 21 | 121 | Plan sowing from this date → |
| LAVA HOT SPRINGS | May 21 | Jun 11 | May 6 | Sep 21 | 118 | Plan sowing from this date → |
| MIDDLE FORK LODGE | May 21 | Jun 13 | May 7 | Sep 18 | 115 | Plan sowing from this date → |
| REYNOLDS | May 21 | Jun 12 | May 4 | Sep 28 | 126 | Plan sowing from this date → |
| ARCO | May 22 | Jun 9 | May 5 | Sep 22 | 119 | Plan sowing from this date → |
| BAYVIEW MODEL BASIN | May 22 | Jun 6 | May 5 | Sep 22 | 122 | Plan sowing from this date → |
| MALAD CITY | May 22 | Jun 16 | May 6 | Sep 20 | 116 | Plan sowing from this date → |
| IDAHO FALLS FANNING FLD | May 23 | Jun 13 | May 7 | Sep 20 | 114 | Plan sowing from this date → |
| MCCAMMON | May 23 | Jun 10 | May 6 | Sep 24 | 121 | Plan sowing from this date → |
| POCATELLO RGNL AP | May 23 | Jun 13 | May 6 | Sep 18 | 117 | Plan sowing from this date → |
| WINCHESTER | May 23 | Jun 19 | May 4 | Sep 25 | 121 | Plan sowing from this date → |
| ARCO 17 SW | May 24 | Jun 15 | May 4 | Oct 1 | 130 | Plan sowing from this date → |
| HOWE | May 24 | Jun 14 | May 6 | Sep 14 | 113 | Plan sowing from this date → |
| NEZPERCE | May 24 | Jun 19 | May 6 | Sep 20 | 116 | Plan sowing from this date → |
| RICHFIELD | May 24 | Jun 14 | May 6 | Sep 26 | 123 | Plan sowing from this date → |
| GRACE | May 29 | Jun 16 | May 11 | Sep 17 | 111 | Plan sowing from this date → |
| SUGAR CITY | May 29 | Jun 18 | May 12 | Sep 13 | 106 | Plan sowing from this date → |
| CASCADE 1 NW | May 30 | Jun 21 | May 10 | Sep 19 | 110 | Plan sowing from this date → |
| DOWNEY | May 31 | Jun 16 | May 13 | Sep 18 | 110 | Plan sowing from this date → |
| OLA | May 31 | Jun 19 | May 8 | Sep 16 | 108 | Plan sowing from this date → |
| POWELL | May 31 | Jun 26 | May 14 | Sep 12 | 102 | Plan sowing from this date → |
| PRICHARD 3 ESE | May 31 | Jun 23 | May 16 | Sep 5 | 95 | Plan sowing from this date → |
| SILVER CITY 5 W | May 31 | Jun 17 | May 4 | Oct 6 | 128 | Plan sowing from this date → |
| GARDEN VALLEY | Jun 1 | Jun 20 | May 13 | Sep 10 | 102 | Plan sowing from this date → |
| GIBBONSVILLE #2 | Jun 1 | Jun 19 | May 14 | Sep 17 | 107 | Plan sowing from this date → |
| MACKAY LOST RVR RS | Jun 1 | Jun 21 | May 13 | Sep 20 | 109 | Plan sowing from this date → |
| MALTA 4 ESE | Jun 1 | Jun 19 | May 10 | Sep 19 | 111 | Plan sowing from this date → |
| HAMER 4 NW | Jun 3 | Jun 21 | May 15 | Sep 11 | 98 | Plan sowing from this date → |
| PIERCE | Jun 3 | Jun 29 | May 17 | Sep 7 | 93 | Plan sowing from this date → |
| MALTA | Jun 5 | Jun 23 | May 19 | Sep 13 | 96 | Plan sowing from this date → |
| SMALL 6N | Jun 5 | Jun 21 | May 11 | Sep 20 | 106 | Plan sowing from this date → |
| LOWMAN | Jun 6 | Jul 1 | May 18 | Sep 4 | 87 | Plan sowing from this date → |
| FAIRFIELD RS | Jun 8 | Jun 28 | May 15 | Sep 14 | 97 | Plan sowing from this date → |
| IDAHO FALLS 16 SE | Jun 9 | Jun 26 | May 19 | Sep 11 | 93 | Plan sowing from this date → |
| MCCALL AP | Jun 10 | Jun 28 | May 21 | Sep 10 | 93 | Plan sowing from this date → |
| MULLAN PASS VOR/DME | Jun 10 | Jun 25 | May 21 | Sep 23 | 104 | Plan sowing from this date → |
| IDAHO FALLS 46 W | Jun 11 | Jul 1 | May 20 | Sep 6 | 89 | Plan sowing from this date → |
| MAY 2SSE | Jun 12 | Jun 29 | May 24 | Sep 6 | 85 | Plan sowing from this date → |
| MONTEVIEW | Jun 12 | Jun 30 | May 21 | Sep 7 | 87 | Plan sowing from this date → |
| YELLOWPINE | Jun 12 | Jul 5 | May 21 | Sep 11 | 88 | Plan sowing from this date → |
| DRIGGS | Jun 13 | Jun 28 | May 27 | Sep 9 | 86 | Plan sowing from this date → |
| CHILLY BARTON FLAT | Jun 14 | Jun 30 | May 27 | Sep 8 | 86 | Plan sowing from this date → |
| TETONIA EXP STN | Jun 15 | Jun 29 | May 24 | Sep 7 | 85 | Plan sowing from this date → |
| HILL CITY 1 W | Jun 16 | Jul 3 | May 31 | Sep 6 | 80 | Plan sowing from this date → |
| PICABO | Jun 16 | Jun 30 | Jun 3 | Sep 9 | 85 | Plan sowing from this date → |
| BERN | Jun 17 | Jul 4 | May 31 | Sep 3 | 77 | Plan sowing from this date → |
| IDAHO CITY | Jun 17 | Jul 4 | May 30 | Sep 5 | 80 | Plan sowing from this date → |
| CRATERS OF THE MOON | Jun 19 | Jul 2 | Jun 5 | Sep 9 | 81 | Plan sowing from this date → |
| MCCALL | Jun 22 | Jul 10 | Jun 3 | Sep 2 | 72 | Plan sowing from this date → |
How to read the three dates
Average is the date by which, in half of the years between 1991 and 2020, the last 32 °F night had already happened. Safe is later: only one year in ten saw a frost after it, which is the date to transplant tomatoes and peppers, both killed by a single frost. Early is the risky end, with a frost after it in nine years out of ten.
Every figure is for the weather station, not for your garden. A valley bottom, a north slope or a spot near a lake can run a week or two either way. Cities are warmer than the countryside around them.
Where the numbers come from
The dates are NOAA's U.S. Climate Normals for 1991 to 2020, computed by the National Centers for Environmental Information for every station with thirty years of daily minimum temperatures. ZIP codes are matched to the nearest such station within 150 km using U.S. Census Bureau ZIP Code Tabulation Area centroids. Stations that never see a frost, such as much of south Florida, report no date and are left out.