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Idaho frost dates by weather station

Idaho has 144 NOAA weather stations with 1991–2020 freeze statistics. Median last spring frost dates run from Apr 2 at Brownlee Dam to Jun 22 at McCall.

144Stations
Apr 2Earliest last frostBrownlee Dam
Jun 22Latest last frostMcCall
216 daysLongest growing seasonBrownlee Dam

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Idaho stations: median (50%) frost dates at 32°F
Station	Last spring frost	First fall frost	Growing season	Elevation
Aberdeen Exp. Station	May 21	Sep 20	118 days	4,405 ft
American Falls	May 4	Oct 8	155 days	4,510 ft
American Falls 6 NE	May 14	Oct 2	138 days	4,415 ft
Arco	May 22	Sep 22	119 days	5,325 ft
Arco 17 SW	May 24	Oct 1	130 days	5,920 ft
Arrowrock Dam	Apr 28	Oct 14	169 days	3,235 ft
Ashton 1n	May 21	Sep 21	121 days	5,212 ft
Bayview Model Basin	May 22	Sep 22	122 days	2,087 ft
Bellevue	May 13	Oct 2	139 days	5,192 ft
Bern	Jun 17	Sep 3	77 days	5,964 ft
Blackfoot Fire Dept	May 5	Oct 3	149 days	4,499 ft
Boise 7 N	May 17	Oct 12	147 days	3,885 ft
Boise Air Terminal	Apr 24	Oct 21	179 days	2,814 ft
Boise Lucky Peak Dam	Apr 30	Oct 22	173 days	2,840 ft
Bonners Ferry	Apr 30	Oct 4	154 days	2,075 ft
Brownlee Dam	Apr 2	Nov 5	216 days	1,844 ft
Bruneau	Apr 17	Oct 17	181 days	2,530 ft
Buhl #2	Apr 25	Oct 15	172 days	3,800 ft
Burley Muni Airport	May 7	Oct 4	150 days	4,142 ft
Cabinet Gorge	May 9	Oct 8	153 days	2,173 ft
Cambridge	May 15	Sep 27	134 days	2,650 ft
Cascade 1 NW	May 30	Sep 19	110 days	4,896 ft
Castleford 2 N	May 17	Sep 29	132 days	3,825 ft
Challis Airport	May 14	Sep 25	131 days	5,033 ft
Chilly Barton Flat	Jun 14	Sep 8	86 days	6,260 ft
Coeur D'alene	Apr 22	Oct 18	179 days	2,133 ft
Cottonwood 2 WSW	May 6	Oct 13	156 days	3,945 ft
Council	May 10	Oct 2	145 days	2,943 ft
Craters Of The Moon	Jun 19	Sep 9	81 days	5,914 ft
Deadwood Lodge	any month	any month	32 days	5,948 ft
Deer Flat Dam	Apr 23	Oct 18	178 days	2,510 ft
Dixie	any month	any month	29 days	5,620 ft
Dixie N	any month	any month	30 days	5,740 ft
Downey	May 31	Sep 18	110 days	4,865 ft
Driggs	Jun 13	Sep 9	86 days	6,120 ft
Dubois Exp. Station	May 18	Sep 30	132 days	5,450 ft
Dworshak Fish Hatchery	Apr 20	Oct 20	182 days	995 ft
Elk City 1ne	any month	any month	64 days	4,058 ft
Elk River	May 16	Sep 23	128 days	2,866 ft
Emmett 2 E	Apr 30	Oct 17	168 days	2,390 ft
Fairfield Ranger Station	Jun 8	Sep 14	97 days	5,065 ft
Fenn Ranger Station	Apr 26	Oct 20	176 days	1,560 ft
Fort Hall 1 NNE	May 20	Sep 20	119 days	4,465 ft
Garden Valley	Jun 1	Sep 10	102 days	3,100 ft
Gibbonsville #2	Jun 1	Sep 17	107 days	4,480 ft
Glenns Ferry	May 1	Oct 3	154 days	2,466 ft
Grace	May 29	Sep 17	111 days	5,550 ft
Grand View 4 NW	Apr 28	Oct 6	162 days	2,400 ft
Grangeville	May 9	Oct 3	146 days	3,300 ft
Hagerman 2 SW	May 3	Oct 1	151 days	2,897 ft
Hamer 4 NW	Jun 3	Sep 11	98 days	4,790 ft
Hazelton	May 7	Oct 5	149 days	4,060 ft
Headquarters	any month	any month	81 days	3,200 ft
Hill City 1 W	Jun 16	Sep 6	80 days	5,100 ft
Homedale 1 SE	Apr 24	Oct 9	169 days	2,230 ft
Howe	May 24	Sep 14	113 days	4,820 ft
Idaho City	Jun 17	Sep 5	80 days	3,965 ft
Idaho Falls - Kifi	May 9	Oct 1	142 days	4,742 ft
Idaho Falls 16 SE	Jun 9	Sep 11	93 days	5,828 ft
Idaho Falls 46 W	Jun 11	Sep 6	89 days	4,938 ft
Idaho Falls Fanning Field	May 23	Sep 20	114 days	4,729 ft
Island Park	any month	any month	49 days	6,290 ft
Jerome	May 2	Oct 14	166 days	3,740 ft
Jerome Co Airport	May 1	Oct 14	165 days	4,048 ft
Kamiah	Apr 29	Oct 5	163 days	1,210 ft
Kellogg	May 14	Sep 26	131 days	2,377 ft
Ketchum Ranger Station	any month	any month	77 days	5,890 ft
Kooskia 5 SSE	Apr 30	Oct 11	162 days	2,330 ft
Lava Hot Springs	May 21	Sep 21	118 days	4,595 ft
Leadore #2	any month	any month	50 days	6,000 ft
Lewiston Nez Perce Co Airport	Apr 6	Oct 26	200 days	1,436 ft
Lifton Pumping Station	May 19	Sep 21	123 days	5,935 ft
Lowell Three Rivers	Apr 16	Oct 25	191 days	1,480 ft
Lowman	Jun 6	Sep 4	87 days	3,920 ft
Mackay Lost River Ranger Station	Jun 1	Sep 20	109 days	5,897 ft
Malad City	May 22	Sep 20	116 days	4,470 ft
Malta	Jun 5	Sep 13	96 days	4,521 ft
Malta 4 ESE	Jun 1	Sep 19	111 days	4,590 ft
Massacre Rocks State Park	May 20	Sep 26	125 days	4,195 ft
May 2sse	Jun 12	Sep 6	85 days	5,050 ft
McCall	Jun 22	Sep 2	72 days	5,025 ft
McCall Airport	Jun 10	Sep 10	93 days	5,013 ft
McCammon	May 23	Sep 24	121 days	4,770 ft
Middle Fork Lodge	May 21	Sep 18	115 days	4,480 ft
Minidoka Dam	May 16	Oct 1	136 days	4,164 ft
Monteview	Jun 12	Sep 7	87 days	4,815 ft
Moscow U Of I	any month	any month	85 days	2,660 ft
Mountain Home	May 2	Oct 8	157 days	3,140 ft
Mullan	May 12	Sep 30	138 days	3,201 ft
Mullan Pass Vor/dme	Jun 10	Sep 23	104 days	6,028 ft
Murphy (desert) Hot Springs	any month	any month	87 days	5,152 ft
Murphy 10 W	May 17	Sep 30	134 days	3,950 ft
Nampa Sugar Factory	Apr 29	Oct 13	164 days	2,470 ft
New Meadows Ranger Station	any month	any month	62 days	3,862 ft
Nezperce	May 24	Sep 20	116 days	3,248 ft
Oakley	May 15	Oct 2	137 days	4,559 ft
Ola	May 31	Sep 16	108 days	3,075 ft
Parma Exp. Station	Apr 27	Oct 9	165 days	2,290 ft
Paul 1ene	May 6	Oct 6	151 days	4,150 ft
Payette	Apr 19	Oct 20	183 days	2,150 ft
Picabo	Jun 16	Sep 9	85 days	4,839 ft
Pierce	Jun 3	Sep 7	93 days	3,080 ft
Plummer 3 WSW	May 11	Oct 5	143 days	2,905 ft
Pocatello 2 NE	May 16	Oct 2	137 days	4,832 ft
Pocatello City	May 2	Oct 11	161 days	4,460 ft
Pocatello Regional Airport	May 23	Sep 18	117 days	4,478 ft
Porthill 1 SW	May 4	Sep 30	145 days	1,799 ft
Potlatch 3 NNE	May 15	Sep 21	126 days	2,760 ft
Powell	May 31	Sep 12	102 days	3,530 ft
Preston	May 16	Sep 28	133 days	4,719 ft
Prichard 3 ESE	May 31	Sep 5	95 days	2,547 ft
Priest River Exp. Station	May 20	Sep 13	114 days	2,371 ft
Red River Ranger Station	any month	any month	59 days	4,350 ft
Rexburg Byu Idaho	May 12	Sep 24	132 days	5,005 ft
Rexburg Madison Co Airport	May 15	Sep 23	129 days	4,858 ft
Reynolds	May 21	Sep 28	126 days	3,930 ft
Richfield	May 24	Sep 26	123 days	4,309 ft
Rigby	May 9	Oct 5	148 days	4,856 ft
Riggins	May 6	Oct 9	155 days	2,056 ft
Saint Anthony	May 17	Sep 22	126 days	4,910 ft
Saint Maries	May 3	Oct 4	152 days	2,151 ft
Salmon-Ksra	May 17	Sep 24	127 days	3,953 ft
Sandpoint Exp. Station	May 8	Sep 28	141 days	2,126 ft
Shoshone 1 WNW	Apr 24	Oct 16	173 days	3,950 ft
Shoup	May 3	Oct 8	157 days	3,400 ft
Silver City 5 W	May 31	Oct 6	128 days	6,160 ft
Small 6n	Jun 5	Sep 20	106 days	5,740 ft
Soda Springs Airport	any month	any month	69 days	5,842 ft
Stanley	any month	any month	13 days	6,249 ft
Stanley Ranger Station	any month	any month	29 days	6,495 ft
Sugar City	May 29	Sep 13	106 days	4,925 ft
Swan Falls Ph	Apr 12	Oct 26	193 days	2,325 ft
Swan Valley	any month	any month	69 days	5,397 ft
Taylor Rch	May 11	Sep 30	140 days	3,835 ft
Tetonia Exp. Station	Jun 15	Sep 7	85 days	6,170 ft
Twin Falls 6 E	May 6	Oct 3	150 days	3,960 ft
Twin Falls Sun Valley Regional Airport	May 9	Oct 4	147 days	4,151 ft
Twin Falls-Kmvt	Apr 30	Oct 9	161 days	3,670 ft
Wallace	May 5	Oct 2	149 days	2,710 ft
Warren	any month	any month	23 days	5,907 ft
Weiser	Apr 23	Oct 13	174 days	2,120 ft
Winchester	May 23	Sep 25	121 days	3,972 ft
Yellowpine	Jun 12	Sep 11	88 days	5,050 ft
Yellowpine Bar	May 2	Oct 10	159 days	2,480 ft

Sources

NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.

Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.