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Frost Date Finder

NOAA 1991–2020 freeze normals

Frost Dates in Idaho

Last and first frost at the 66 NOAA stations behind this site's Idaho pages.

At the middle station of the 66 in Idaho where a freeze comes every year, the last spring frost (50%) is May 8 and the first fall frost October 3, a freeze-free season of 149 days. The last frost is earliest at Lewiston (Lewiston Nez Perce Co Airport, ID, April 6) and latest at Montpelier (Bern, ID, June 17), 72 days apart. The season runs from 77 days at Montpelier to 200 at Lewiston.

42 of these stations were also in NOAA's previous normals, for 1981–2010. Between the two, the median station's freeze-free season grew 8 days longer, with the last spring frost 4 days earlier and the first fall frost 5 days later; the season lengthened at 36 stations and shortened at 5. The two periods share twenty years, so the change reflects mostly 2011–2020 against 1981–1990.

Idaho places by frost date

Frost dates of the Idaho places with a page, largest first
PlaceZIPLast frostFirst frostSeasonWinters with 32°F
Meridian83646April 29October 13164 d100%
Twin Falls83301May 9October 4147 d100%
Boise83709April 24October 21179 d100%
Post Falls83854April 22October 18179 d100%
Rexburg83440May 12September 24132 d100%
Idaho Falls83401May 9October 1142 d100%
Pocatello83201May 2October 11161 d100%
Lewiston83501April 6October 26200 d100%
Eagle83616May 17October 12147 d100%
Caldwell83607April 23October 18178 d100%
Idaho Falls83402May 23September 20114 d100%
Blackfoot83221May 5October 3149 d100%
Moscow83843April 29October 2159 d100%
Rigby83442May 9October 5148 d100%
Chubbuck83202May 20September 20119 d100%
Mountain Home83647May 2October 8157 d100%
Jerome83338May 1October 14165 d100%
Boise83716April 28October 14169 d100%
Sandpoint83864May 8September 28141 d100%
Burley83318May 7October 4150 d100%
Emmett83617April 30October 17168 d100%
Rupert83350May 16October 1136 d100%
Hailey83333May 13October 2139 d100%
Payette83661April 19October 20183 d100%
Buhl83316April 25October 15172 d100%
Preston83263May 16September 28133 d100%
Kimberly83341May 6October 3150 d100%
Weiser83672April 23October 13174 d100%
Bonners Ferry83805April 30October 4154 d100%
Saint Anthony83445May 17September 22126 d100%
Mccall83638June 10September 1093 d100%
Athol83801May 22September 22122 d100%
St Maries83861May 3October 4152 d100%
Gooding83330May 3October 1151 d100%
Priest River83856May 20September 13114 d100%
Salmon83467May 17September 24127 d100%
American Falls83211May 4October 8155 d100%
Orofino83544April 20October 20182 d100%
Parma83660April 27October 9165 d100%
Grangeville83530May 9October 3146 d100%
Victor83455June 13September 986 d100%
Wendell83355May 2October 14166 d100%
Wilder83676April 24October 9169 d100%
Malad City83252May 22September 20116 d100%
Kamiah83536April 29October 5163 d100%
Soda Springs83276May 29September 17111 d100%
Melba83641April 12October 26193 d100%
Montpelier83254June 17September 377 d100%
Aberdeen83210May 21September 20118 d100%
Moscow83844May 15September 21126 d100%
Paul83347May 6October 6151 d100%
Kellogg83837May 14September 26131 d100%
Shoshone83352April 24October 16173 d100%
Sugar City83448May 29September 13106 d100%
Cascade83611May 30September 19110 d100%
Iona83427June 9September 1193 d100%
Cottonwood83522May 6October 13156 d100%
Ashton83420May 21September 21121 d100%
Inkom83245May 23September 24121 d100%
Kooskia83539April 16October 25191 d100%
Hazelton83335May 7October 5149 d100%
Council83612May 10October 2145 d100%
Tetonia83452June 15September 785 d100%
Challis83226May 14September 25131 d100%
Garden Valley83622June 1September 10102 d100%
Osburn83849May 5October 2149 d100%

50% dates from NOAA NCEI U.S. Climate Normals 1991–2020, one row per station; a state page is published when at least 5 stations stand behind its pages. Where a freeze comes in fewer than nine winters in ten, the dates describe the winters that have one.