Montana Frost Dates: Last and First Frost by Town

245 NOAA weather stations · 1991–2020 U.S. Climate Normals · Data updated 2026-10-29

Quick answer

Across Montana's 216 NOAA stations with regular frost, the median last spring frost is May 20 and the median first fall frost is September 22. Last frost dates range from April 30 at Norris Madison Pwr House to June 18 at Tizer Gardens, so enter your ZIP code below for the station nearest you.

How frost dates vary across Montana

Elevation matters: across Montana's stations, each 1,000 ft of elevation delays the median last frost by about 6 days.
North vs south: stations in the northern third of the state (north of 47.9°N) reach their median last frost about 5 days earlier than the southern third (south of 46.5°N).
Safety margin: the median 10%-risk date (June 4) is about 15 days after the median last frost. Waiting until then cuts the chance of a killing frost on tender transplants from 1 in 2 to 1 in 10.

Frost dates at Montana's major weather stations

These National Weather Service stations, mostly at airports, have the longest and most complete records in the state.


Baker Municipal Airport	2,971	May 16	May 29	Sep 26	132
Billings Logan Intl Airport	3,581	May 4	May 18	Oct 7	156
Bozeman Gallatin Field	4,427	May 26	Jun 12	Sep 16	112
Butte Bert Mooney Airport	5,506	Jun 13	Jul 1	Sep 5	83
Cut Bank Municipal Airport	3,838	May 24	Jun 5	Sep 15	113
Dillon 18 WSW	5,971	Any month	Any month	Any month	72
Dillon Airport	5,200	Jun 2	Jun 21	Sep 13	101
Drummond Aviation	4,000	Any month	Any month	Any month	80
Glasgow Intl Airport	2,285	May 6	May 18	Sep 30	145
Great Falls Intl Airport	3,664	May 19	Jun 2	Sep 24	126
Havre City County Airport	2,585	May 15	May 27	Sep 23	129
Helena Regional Airport	3,828	May 9	May 25	Sep 30	142
Jordan Airport	2,662	May 18	May 31	Sep 20	123
Lewistown 42 WSW	5,070	Jun 15	Jul 8	Sep 4	77
Lewistown Municipal Airport	4,145	May 23	Jun 8	Sep 21	119
Livingston Mission Field	4,643	May 27	Jun 14	Sep 14	108
Miles City F Wiley Field	2,624	May 8	May 21	Sep 30	144
Missoula Intl Airport	3,192	May 16	Jun 1	Sep 26	130
St Marie	2,756	May 13	May 26	Sep 27	134
St. Mary 1 SSW	4,555	Jun 3	Jun 23	Sep 8	94
Superior	2,710	May 17	Jun 8	Sep 23	125
Wolf Point 29 ENE	2,085	May 24	Jun 6	Sep 14	110
Wolf Point 34 NE	2,643	May 13	May 25	Sep 28	137
Wolf Point Intl Airport	1,986	May 16	May 29	Sep 20	125

All 245 stations in Montana

Last frost and first frost are medians: a 50% chance of a 32°F night after (spring) or before (fall) that date. 10% risk is the spring date with only a 1-in-10 chance of a later frost. Click a column to sort.

Filter by station name


Adel	5,017	Jun 4	Jun 22	Sep 12	98
Alberton	3,060	May 18	Jun 6	Sep 25	126
Albion 1 N	3,312	Jun 2	Jun 21	Sep 6	95
Alder 17 S	5,850	Jun 6	Jun 25	Sep 14	98
Alder 19S	5,749	Any month	Any month	Any month	77
Anaconda	5,230	Jun 1	Jun 25	Sep 14	105
Augusta	4,070	May 19	May 31	Sep 21	125
Austin 1 W	4,851	Jun 4	Jun 18	Sep 14	100
Baker	2,933	May 12	May 27	Sep 26	135
Baker Municipal Airport	2,971	May 16	May 29	Sep 26	132
Biddle 8 SW	3,631	May 14	May 27	Sep 28	134
Big Sandy	2,770	May 17	Jun 4	Sep 25	128
Big Sky 2WNW	6,590	Any month	Any month	Any month	50
Big Timber	4,100	May 14	May 27	Sep 26	133
Bigfork 13 S	2,979	May 1	May 16	Oct 15	165
Billings Logan Intl Airport	3,581	May 4	May 18	Oct 7	156
Billings WFO	3,185	May 5	May 21	Oct 3	149
Billings Wtp	3,097	May 10	May 24	Oct 1	142
Blackleaf	4,235	Jun 9	Jul 2	Sep 3	86
Boulder	4,904	Jun 7	Jun 25	Sep 8	90
Bozeman 6 W Experiment Farm	4,775	May 23	Jun 12	Sep 23	123
Bozeman Gallatin Field	4,427	May 26	Jun 12	Sep 16	112
Bozeman Montana State University	4,913	May 26	Jun 14	Sep 22	116
Brady 27 ENE (the Knees)	3,325	May 13	May 29	Sep 29	137
Brandenberg	2,770	May 18	May 30	Sep 22	126
Bredette	2,313	May 20	Jun 1	Sep 21	122
Bridger 2 N	3,583	May 14	May 30	Sep 24	129
Broadus	3,032	May 16	May 29	Sep 28	135
Brockway 3 WSW	2,630	May 20	Jun 5	Sep 19	121
Busby	3,430	May 23	Jun 7	Sep 15	113
Butte Bert Mooney Airport	5,506	Jun 13	Jul 1	Sep 5	83
Bynum 4 SSE	4,039	May 16	May 28	Sep 27	133
Carlyle 13 NW	3,145	May 18	May 31	Sep 29	134
Carter 14 W	3,450	May 23	Jun 9	Sep 23	120
Cascade 20 SSE	4,600	Any month	Any month	Any month	70
Cascade 5 S	3,360	May 21	Jun 6	Sep 19	120
Chester	3,132	May 24	Jun 9	Sep 17	115
Chinook	2,420	May 14	May 27	Sep 23	130
Chinook 35SE	3,360	May 23	Jun 3	Sep 23	121
Choteau	3,845	May 28	Jun 20	Sep 12	104
Choteau 8NE	3,741	May 20	Jun 4	Sep 22	123
Circle	2,480	May 17	May 31	Sep 22	126
Cohagen	2,720	May 25	Jun 9	Sep 14	110
Colstrip	3,218	May 15	May 28	Sep 30	138
Columbus	3,602	May 27	Jun 12	Sep 14	108
Conrad	3,550	May 20	Jun 3	Sep 19	119
Content 4 NNE	2,325	May 25	Jun 8	Sep 14	110
Cooke City 2 W	7,483	Any month	Any month	Any month	36
Creston	2,935	May 12	May 26	Sep 25	134
Culbertson	1,940	May 21	Jun 3	Sep 20	120
Cut Bank Municipal Airport	3,838	May 24	Jun 5	Sep 15	113
Darby	3,880	May 24	Jun 14	Sep 23	118
Deer Lodge 3 W	4,850	Any month	Any month	Any month	65
Del Bonita	4,337	May 28	Jun 12	Sep 16	110
Denton	3,610	Jun 1	Jun 26	Sep 11	101
Dillon 18 WSW	5,971	Any month	Any month	Any month	72
Dillon Airport	5,200	Jun 2	Jun 21	Sep 13	101
Dillon U Of Montana Western	5,129	Jun 5	Jun 23	Sep 13	98
Divide	5,350	Jun 10	Jul 2	Sep 7	85
Drummond Aviation	4,000	Any month	Any month	Any month	80
Dunkirk 19NNE	3,323	May 23	Jun 8	Sep 14	112
E Glacier	4,806	Jun 8	Jul 1	Sep 5	88
Ekalaka	3,432	May 20	Jun 1	Sep 23	126
Elliston	5,080	Jun 9	Jun 26	Sep 8	91
Ennis	4,953	Jun 16	Jul 6	Sep 4	78
Eureka Ranger Station	2,532	May 11	May 25	Sep 27	138
Fairfield	3,983	May 13	Jun 1	Sep 27	135
Flatwillow 4 ENE	3,292	May 16	May 31	Sep 28	132
Forsyth	2,515	May 9	May 21	Sep 29	142
Fort Assiniboine	2,675	May 15	May 28	Sep 24	130
Fort Belknap 2 SW	2,527	May 16	May 28	Sep 22	128
Fort Benton	2,649	May 15	May 30	Sep 22	129
Fort Peck Pwr Plt	2,071	May 8	May 20	Oct 1	145
Fortine 1 N	3,000	May 16	Jun 3	Sep 18	121
Gardiner	5,275	May 21	Jun 9	Sep 27	128
Geraldine	3,145	May 14	May 28	Sep 26	134
Gibson 2 NE	4,444	May 27	Jun 12	Sep 18	113
Gibson Dam	4,590	Jun 12	Jul 5	Sep 8	88
Gildford	2,820	May 24	Jun 7	Sep 15	114
Glasgow #2	2,090	May 3	May 15	Oct 1	151
Glasgow Intl Airport	2,285	May 6	May 18	Sep 30	145
Glen 4 N	5,054	Any month	Any month	Any month	71
Glendive	2,075	May 3	May 16	Oct 4	153
Goldbutte 7 N	3,498	Any month	Any month	Any month	77
Grass Range	3,490	May 20	Jun 6	Sep 24	126
Great Falls 16ST	3,505	May 6	May 19	Oct 1	147
Great Falls Intl Airport	3,664	May 19	Jun 2	Sep 24	126
Great Falls WFO	3,705	May 12	May 27	Sep 28	138
Hamilton	3,585	May 21	Jun 6	Sep 22	122
Hardin	2,880	May 13	May 26	Sep 29	135
Harlem	2,371	May 16	May 31	Sep 21	125
Harlem 20S	2,695	May 24	Jun 11	Sep 22	118
Harlowton	4,222	May 23	Jun 6	Sep 16	113
Harlowton 11NW	4,954	May 30	Jun 17	Sep 20	110
Haugan 1 W	3,160	Any month	Any month	Any month	90
Havre City County Airport	2,585	May 15	May 27	Sep 23	129
Hebgen Dam	6,489	Jun 15	Jul 7	Sep 10	87
Helena Regional Airport	3,828	May 9	May 25	Sep 30	142
Heron 2 NW	2,240	May 20	Jun 5	Sep 20	119
Highwood 7 NE	3,600	May 7	May 21	Oct 2	149
Hinsdale 4 SW	2,805	May 15	May 30	Sep 26	132
Holter Dam	3,487	May 19	Jun 8	Sep 24	124
Hungry Horse Dam	3,160	May 9	May 30	Oct 1	141
Huntley Experiment Station	3,034	May 12	May 26	Sep 25	136
Hysham	2,669	May 10	May 22	Sep 29	141
Hysham 25 SSE	3,100	May 26	Jun 13	Sep 16	111
Ingomar 9 E	2,800	May 21	Jun 4	Sep 19	120
Jackson	6,480	Any month	Any month	Any month	51
Joliet	3,838	May 29	Jun 17	Sep 15	107
Joplin	3,323	May 21	Jun 6	Sep 19	119
Jordan	2,620	May 21	Jun 2	Sep 18	118
Jordan Airport	2,662	May 18	May 31	Sep 20	123
Judith Gap	4,630	Jun 1	Jun 16	Sep 15	104
Judith Gap 13 E	4,791	Jun 3	Jun 25	Sep 15	100
Kalispell Glacier Airport	2,957	May 31	Jun 22	Sep 10	100
Lakeview	6,710	Any month	Any month	Any month	66
Laurin 2NE	5,198	May 24	Jun 13	Sep 22	117
Lennep 5 SW	5,600	Any month	Any month	Any month	65
Lewistown	3,911	May 14	May 27	Sep 28	135
Lewistown 11 SSE	4,965	May 31	Jun 18	Sep 14	105
Lewistown 11ESE	5,028	May 19	Jun 1	Sep 25	128
Lewistown 42 WSW	5,070	Jun 15	Jul 8	Sep 4	77
Lewistown Municipal Airport	4,145	May 23	Jun 8	Sep 21	119
Libby	2,140	May 10	May 26	Sep 26	137
Libby 1 NE Ranger Station	2,096	May 23	Jun 7	Sep 21	120
Libby 32 SSE	3,440	Any month	Any month	Any month	44
Libby Dam (base)	2,110	May 11	May 27	Oct 1	142
Lima	6,279	Jun 11	Jun 30	Sep 10	89
Lincoln Ranger Station	4,575	Any month	Any month	Any month	65
Lindbergh Lake	4,320	May 20	Jun 7	Sep 22	120
Livingston 12 S	5,044	May 19	Jun 11	Sep 25	125
Livingston Mission Field	4,643	May 27	Jun 14	Sep 14	108
Logan Landfill	4,243	May 26	Jun 12	Sep 15	111
Loma	2,578	May 20	Jun 3	Sep 19	120
Malta	2,262	May 10	May 22	Sep 29	139
Malta 35 S	2,615	May 16	May 29	Sep 23	128
Malta 7 E	2,231	May 7	May 21	Sep 28	143
Martinsdale 3 NNW	4,800	Jun 3	Jun 25	Sep 8	94
Medicine Lake 3 SE	1,942	May 16	May 30	Sep 18	125
Melstone	2,932	May 10	May 23	Sep 29	141
Melville 4 W	5,365	Jun 9	Jun 27	Sep 7	88
Mildred 5 N	2,482	May 20	Jun 2	Sep 22	124
Miles City F Wiley Field	2,624	May 8	May 21	Sep 30	144
Millegan 14 SE	4,970	Jun 11	Jul 3	Sep 6	86
Missoula 2 NE	3,420	May 10	May 28	Oct 1	143
Missoula 6 NW WFO	3,197	May 6	May 19	Oct 4	151
Missoula Intl Airport	3,192	May 16	Jun 1	Sep 26	130
Mizpah 4 NNW	2,480	May 22	Jun 7	Sep 15	117
Moccasin Experiment Station	4,300	May 28	Jun 19	Sep 20	112
Moorhead 9 NE	3,220	May 17	May 31	Sep 22	126
Mosby 4 ENE	2,910	May 5	May 26	Oct 4	151
Mystic Lake	6,544	Jun 5	Jun 21	Sep 14	99
Nashua #2	2,067	May 12	May 26	Sep 24	134
Neihart 8 NNW	5,230	Jun 6	Jun 28	Sep 12	99
Norris Madison Pwr House	4,745	Apr 30	May 14	Oct 10	162
Nye #2	4,840	Jun 1	Jun 21	Sep 11	100
Olney	3,165	Any month	Any month	Any month	60
Opheim 10 N	2,878	Jun 1	Jun 18	Sep 7	99
Opheim 12 SSE	2,936	Jun 5	Jun 23	Sep 2	89
Ovando 9 SSE	4,325	Any month	Any month	Any month	67
Phillipsburg Ranger Station	5,270	Any month	Any month	Any month	65
Plentywood	2,048	May 25	Jun 8	Sep 14	111
Plevna	2,780	May 21	Jun 4	Sep 20	121
Polebridge	3,520	Any month	Any month	Any month	40
Polson	3,010	May 10	May 26	Oct 5	147
Pompeys Pillar 15N	3,390	May 22	Jun 7	Sep 22	121
Port Of Morgan	2,830	May 19	Jun 2	Sep 22	124
Potomac	3,690	Any month	Any month	Any month	45
Powderville 8 NNE	2,800	May 13	May 31	Sep 25	132
Rapelje	4,068	May 24	Jun 11	Sep 21	116
Raymond Border Station	2,345	May 19	Jun 1	Sep 23	125
Raynesford 2 NNW	4,215	May 22	Jun 9	Sep 23	123
Red Lodge	5,646	Jun 3	Jun 18	Sep 19	106
Redstone	2,106	May 28	Jun 13	Sep 7	101
Ridgeway 1 S	3,316	May 17	Jun 1	Sep 22	127
Rock Springs	3,024	May 15	May 27	Sep 25	132
Rogers Pass 9 NNE	4,200	May 21	Jun 8	Sep 15	115
Roundup	3,200	May 20	Jun 2	Sep 21	124
Roundup 15 SW	3,386	May 22	Jun 4	Sep 15	114
Roy 8 NE	3,085	May 14	May 29	Sep 24	134
Rudyard 19S	2,878	May 23	Jun 3	Sep 19	119
Rudyard 21 N	3,000	May 30	Jun 15	Sep 11	103
Ryegate	3,650	May 17	May 30	Sep 23	127
Ryegate 18 NNW	4,440	May 26	Jun 13	Sep 18	112
Saco 1 NNW	2,185	May 15	May 26	Sep 23	130
Saint Ignatius	2,915	May 12	Jun 1	Oct 2	142
Saint Regis 1 NE	2,660	Any month	Any month	Any month	101
Sand Creek	2,910	May 12	May 27	Sep 27	136
Savage	1,978	May 12	May 26	Sep 25	135
Scobey 4 NW	2,390	May 28	Jun 13	Sep 6	99
Seeley Lake Ranger Station	4,100	Any month	Any month	Any month	74
Shelby	3,325	May 23	Jun 6	Sep 16	115
Shonkin 7 S	4,300	May 24	Jun 10	Sep 21	119
Sidney	1,933	May 11	May 25	Sep 27	137
Silver Gate	7,495	Any month	Any month	Any month	31
Simpson 6 N - Wildhorse	2,815	May 26	Jun 8	Sep 15	110
Skq Dam	2,730	May 15	Jun 1	Sep 28	134
Sonnette 7 SW	3,914	May 25	Jun 7	Sep 19	115
St Marie	2,756	May 13	May 26	Sep 27	134
St Mary	4,560	Jun 12	Jul 3	Sep 5	82
St. Mary 1 SSW	4,555	Jun 3	Jun 23	Sep 8	94
Stanford	4,860	May 25	Jun 15	Sep 21	118
Stevensville	3,375	May 22	Jun 13	Sep 19	115
Sula 14 NE	5,155	Any month	Any month	Any month	39
Sula 3 ENE	4,475	Any month	Any month	Any month	59
Sun River 4 S	3,600	Jun 2	Jun 21	Sep 10	96
Sunburst 8 E	3,700	May 17	May 31	Sep 25	129
Superior	2,710	May 17	Jun 8	Sep 23	125
Swan Lake	3,100	May 17	Jun 4	Sep 19	121
Sweetgrass	3,510	May 15	May 28	Sep 25	132
Terry	2,250	May 12	May 25	Sep 28	137
Terry 21 NNW	3,142	May 26	Jun 13	Sep 17	113
Thompson Falls Ph	2,380	May 7	May 19	Oct 4	150
Tiber Dam	2,850	May 16	May 30	Sep 23	129
Tizer Gardens	4,672	Jun 18	Jul 3	Sep 5	81
Townsend 3SE	3,964	May 19	Jun 2	Sep 19	122
Trident	4,036	May 9	May 24	Sep 27	139
Trout Creek Ranger Station	2,356	May 20	Jun 9	Sep 21	122
Troy	1,929	May 14	May 31	Sep 25	132
Turner 11N	2,982	May 19	Jun 1	Sep 21	124
Twin Bridges	4,625	Jun 8	Jul 1	Sep 2	82
Valentine	2,905	May 18	May 31	Sep 21	124
Valier	3,807	May 17	May 31	Sep 24	129
Vida 6 NE	2,284	May 16	May 31	Sep 22	129
Virginia City	5,773	Jun 4	Jun 23	Sep 18	106
W Glacier	3,148	May 18	Jun 4	Sep 20	124
W Yellowstone Gateway	6,679	Any month	Any month	Any month	33
Westby	2,103	May 18	May 30	Sep 21	125
Western Agricultural Rsch Center	3,608	May 23	Jun 10	Sep 21	118
White Sulphur Springs #2	5,040	Jun 4	Jun 20	Sep 11	97
Whitefish	3,100	May 16	Jun 6	Sep 25	129
Wibaux 2 E	2,696	May 27	Jun 13	Sep 16	112
Wilsall 1S	5,015	Jun 4	Jun 23	Sep 6	92
Wilsall 8 ENE	5,865	Jun 8	Jun 30	Sep 7	89
Winifred	3,243	May 16	May 30	Sep 23	127
Wisdom	6,060	Any month	Any month	Any month	22
Wise River 3 WNW	5,730	Any month	Any month	Any month	27
Wolf Point	2,090	May 8	May 20	Sep 28	143
Wolf Point 29 ENE	2,085	May 24	Jun 6	Sep 14	110
Wolf Point 34 NE	2,643	May 13	May 25	Sep 28	137
Wolf Point Intl Airport	1,986	May 16	May 29	Sep 20	125
Wyola 1 SW	3,730	May 21	Jun 2	Sep 17	117
Yaak 9NNE	3,085	Any month	Any month	Any month	74
Yellowtail Dam	3,305	May 7	May 24	Oct 5	151
Zortman	4,035	May 18	Jun 1	Sep 23	126

Frequently asked questions

When is the last frost in Montana?

The median last spring frost (32°F) across Montana's NOAA weather stations is May 20, based on 1991–2020 climate normals. It ranges from April 30 at Norris Madison Pwr House to June 18 at Tizer Gardens. For a safer planting date, use the 10%-risk date; the state median for that is June 4.

When is the first frost in Montana?

The median first fall frost across Montana's stations is September 22. The earliest median first frost is September 2 at Opheim 12 SSE, and the latest is October 15 at Bigfork 13 S.

How long is the growing season in Montana?

The median frost-free season is 123 days across Montana's stations, from 77 days at Lewistown 42 WSW to 165 days at Bigfork 13 S.

When should I plant tomatoes in Montana?

Plant tomatoes outdoors after your local last frost, ideally after the 10%-risk date when nights stay above 50°F. At a typical Montana station that means starting seeds indoors 6–8 weeks before May 20 and transplanting from about June 4. Check your ZIP code, because dates vary by weeks across the state.

Can it frost in summer in Montana?

Yes, at 29 stations in Montana a 32°F night is possible in any month, mostly at high elevation or far north. There is no reliable frost-free season there; use cold-hardy crops and row covers.

How to use these dates

Frost dates are 30-year averages from NOAA, not forecasts. Use them to plan seed starting and planting, then watch the 10-day forecast as the date approaches. Cold air settles in valleys and low spots, so a garden at the bottom of a slope can frost a week or more later in spring than the nearest station shows.

Ready to plan? The planting calendar by ZIP code turns these dates into start-indoors, transplant and sowing dates for 30 crops.

Sources and method

Dates are the 32°F freeze probabilities published in the NOAA NCEI 1991–2020 U.S. Climate Normals for each station. Station names are NOAA's, lightly expanded for readability. See the methodology or download the full table.