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Frost Date Finder

NOAA 1991–2020 freeze normals

Frost Dates in Montana

Last and first frost at the 69 NOAA stations behind this site's Montana pages.

At the middle station of the 69 in Montana where a freeze comes every year, the last spring frost (50%) is May 17 and the first fall frost September 23, a freeze-free season of 126 days. The last frost is earliest at Bigfork (Bigfork 13 S, MT, May 1) and latest at Clancy (Tizer Gardens, MT, June 18), 48 days apart. The season runs from 78 days at Ennis to 165 at Bigfork.

50 of these stations were also in NOAA's previous normals, for 1981–2010. Between the two, the median station's freeze-free season grew 2 days longer, with the last spring frost 1 day earlier and the first fall frost 2 days later; the season lengthened at 36 stations and shortened at 13. The two periods share twenty years, so the change reflects mostly 2011–2020 against 1981–1990.

Montana places by frost date

Frost dates of the Montana places with a page, largest first
PlaceZIPLast frostFirst frostSeasonWinters with 32°F
Kalispell59901May 31September 10100 d100%
Billings59102May 5October 3149 d100%
Bozeman59718May 23September 23123 d100%
Billings59101May 10October 1142 d100%
Bozeman59715May 26September 22116 d100%
Billings59105May 4October 7156 d100%
Butte59701June 13September 583 d100%
Great Falls59405May 6October 1147 d100%
Helena59601May 9September 30142 d100%
Missoula59801May 10October 1143 d100%
Great Falls59404May 19September 24126 d100%
Belgrade59714May 26September 16112 d100%
Missoula59808May 6October 4151 d100%
Columbia Falls59912May 16September 25129 d100%
Hamilton59840May 21September 22122 d100%
Livingston59047May 27September 14108 d100%
Havre59501May 15September 23129 d100%
Stevensville59870May 22September 19115 d100%
Miles City59301May 8September 30144 d100%
Polson59860May 10October 5147 d100%
Libby59923May 11October 1142 d100%
Anaconda59711June 1September 14105 d100%
Bigfork59911May 1October 15165 d100%
Lewistown59457May 23September 21119 d100%
Sidney59270May 11September 27137 d100%
Glendive59330May 3October 4153 d100%
Dillon59725June 5September 1398 d100%
Missoula59804May 16September 26130 d100%
Browning59417June 8September 588 d100%
Corvallis59828May 23September 21118 d100%
Deer Lodge59722June 9September 891 d100%
Manhattan59741May 26September 15111 d100%
Wolf Point59201May 8September 28143 d100%
Clancy59634June 18September 581 d100%
Eureka59917May 11September 27138 d100%
Three Forks59752May 9September 27139 d100%
Hardin59034May 13September 29135 d100%
Cut Bank59427May 24September 15113 d100%
Roundup59072May 20September 21124 d100%
Glasgow59230May 3October 1151 d100%
Townsend59644May 19September 19122 d100%
Columbus59019May 27September 14108 d100%
Plains59859May 17September 23125 d100%
Shepherd59079May 12September 25136 d100%
Conrad59425May 20September 19119 d100%
St Ignatius59865May 12October 2142 d100%
Box Elder59521May 17September 25128 d100%
Red Lodge59068June 3September 19106 d100%
Shelby59474May 23September 16115 d100%
Troy59935May 14September 25132 d100%
Big Timber59011May 14September 26133 d100%
Poplar59255May 24September 14110 d100%
Thompson Falls59873May 7October 4150 d100%
Choteau59422May 16September 27133 d100%
Malta59538May 10September 29139 d100%
Lame Deer59043May 23September 15113 d100%
Ennis59729June 16September 478 d100%
Harlem59526May 16September 22128 d100%
Boulder59632June 7September 890 d100%
Frenchtown59834May 18September 25126 d100%
Forsyth59327May 15September 30138 d100%
Darby59829May 24September 23118 d100%
Chinook59523May 14September 23130 d100%
Joliet59041May 29September 15107 d100%
Baker59313May 16September 26132 d100%
West Yellowstone59758June 15September 1087 d100%
Fairfield59436May 13September 27135 d100%
Trout Creek59874May 20September 21122 d100%
Cascade59421May 21September 19120 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.