Frost dates in Montana
Across Montana's 216 NOAA stations with a frost every year, the typical last spring frost ranges from April 30 at Norris Madison Power House (4,740 feet above sea level) to June 18 at Tizer Gardens (4,670 feet above sea level). The middle station's date is May 20.
Look up your ZIP code
Last frost across Montana
The frost-free season runs from 77 days at Lewistown 42 WSW to 165 days at Bigfork 13 S.
At 29 stations, all high or far north, frost is possible in every month.
These are typical dates: in half of springs the last frost comes later. Each place's page, and each ZIP code lookup, also gives the late-year date, after which only 1 spring in 10 has a frost. That's the safer date for tender plants.
Frost dates for Montana's larger places
| Place | Last spring frost | First fall frost | Season | Zone |
|---|---|---|---|---|
| Billings | May 5 | October 3 | 149 days | 5a |
| Great Falls | May 6 | October 1 | 147 days | 4b |
| Missoula | May 16 | September 26 | 130 days | 5b |
Typical (1-in-2) dates. Each place's page has the early and late years, a planting calendar and a printable planner. Zones are for the ZIP code nearest each place's center.
Hardiness zones in Montana
Montana's 399 ZIP codes in the USDA list fall in zones 3b to 6b: 3b (6 percent), 4a (18 percent), 4b (32 percent), 5a (28 percent), 5b (8 percent), 6a (8 percent) and 6b (under 1 percent). Compared with the 2012 map, 57 percent of them moved to a warmer half zone (19 by a full zone or more), 42 percent stayed the same and 4 moved to a colder one.
A hardiness zone is about the coldest night of winter, which decides which shrubs, trees and perennials survive. Frost dates are about spring and fall, which decide when to plant. You need both. Read more about what the zones mean and what changed in 2023.
Every NOAA station in Montana
All 245 stations in Montana with frost statistics in NOAA's 1991 to 2020 normals, from A to Z. Station names are usually a town, an airport, or a distance and direction from a town. Find one near you and at a similar elevation.
| Station | Elevation (feet) | Last spring frost | First fall frost | Season (days) |
|---|---|---|---|---|
| Adel | 5,020 | June 4 | September 12 | 98 |
| Alberton | 3,060 | May 18 | September 25 | 126 |
| Albion 1 N | 3,310 | June 2 | September 6 | 95 |
| Alder 17 S | 5,850 | June 6 | September 14 | 98 |
| Alder 19 S | 5,750 | Frost possible any month | 77 | |
| Anaconda | 5,230 | June 1 | September 14 | 105 |
| Augusta | 4,070 | May 19 | September 21 | 125 |
| Austin 1 W | 4,850 | June 4 | September 14 | 100 |
| Baker | 2,930 | May 12 | September 26 | 135 |
| Baker Municipal Airport | 2,970 | May 16 | September 26 | 132 |
| Biddle 8 SW | 3,630 | May 14 | September 28 | 134 |
| Big Sandy | 2,770 | May 17 | September 25 | 128 |
| Big Sky 2 WNW | 6,590 | Frost possible any month | 50 | |
| Big Timber | 4,100 | May 14 | September 26 | 133 |
| Bigfork 13 S | 2,980 | May 1 | October 15 | 165 |
| Billings Logan International Airport | 3,580 | May 4 | October 7 | 156 |
| Billings WFO | 3,190 | May 5 | October 3 | 149 |
| Billings WTP | 3,100 | May 10 | October 1 | 142 |
| Blackleaf | 4,240 | June 9 | September 3 | 86 |
| Boulder | 4,900 | June 7 | September 8 | 90 |
| Bozeman 6 W Exp Farm | 4,770 | May 23 | September 23 | 123 |
| Bozeman Gallatin Field | 4,430 | May 26 | September 16 | 112 |
| Bozeman Montana State Univ | 4,910 | May 26 | September 22 | 116 |
| Brady 27 ENE (the Knees) | 3,330 | May 13 | September 29 | 137 |
| Brandenberg | 2,770 | May 18 | September 22 | 126 |
| Bredette | 2,310 | May 20 | September 21 | 122 |
| Bridger 2 N | 3,580 | May 14 | September 24 | 129 |
| Broadus | 3,030 | May 16 | September 28 | 135 |
| Brockway 3 WSW | 2,630 | May 20 | September 19 | 121 |
| Busby | 3,430 | May 23 | September 15 | 113 |
| Butte Bert Mooney Airport | 5,510 | June 13 | September 5 | 83 |
| Bynum 4 SSE | 4,040 | May 16 | September 27 | 133 |
| Carlyle 13 NW | 3,150 | May 18 | September 29 | 134 |
| Carter 14 W | 3,450 | May 23 | September 23 | 120 |
| Cascade 20 SSE | 4,600 | Frost possible any month | 70 | |
| Cascade 5 S | 3,360 | May 21 | September 19 | 120 |
| Chester | 3,130 | May 24 | September 17 | 115 |
| Chinook | 2,420 | May 14 | September 23 | 130 |
| Chinook 35 SE | 3,360 | May 23 | September 23 | 121 |
| Choteau | 3,850 | May 28 | September 12 | 104 |
| Choteau 8 NE | 3,740 | May 20 | September 22 | 123 |
| Circle | 2,480 | May 17 | September 22 | 126 |
| Cohagen | 2,720 | May 25 | September 14 | 110 |
| Colstrip | 3,220 | May 15 | September 30 | 138 |
| Columbus | 3,600 | May 27 | September 14 | 108 |
| Conrad | 3,550 | May 20 | September 19 | 119 |
| Content 4 NNE | 2,330 | May 25 | September 14 | 110 |
| Cooke City 2 W | 7,480 | Frost possible any month | 36 | |
| Creston | 2,940 | May 12 | September 25 | 134 |
| Culbertson | 1,940 | May 21 | September 20 | 120 |
| Cut Bank Municipal Airport | 3,840 | May 24 | September 15 | 113 |
| Darby | 3,880 | May 24 | September 23 | 118 |
| Deer Lodge 3 W | 4,850 | Frost possible any month | 65 | |
| Del Bonita | 4,340 | May 28 | September 16 | 110 |
| Denton | 3,610 | June 1 | September 11 | 101 |
| Dillon 18 WSW | 5,970 | Frost possible any month | 72 | |
| Dillon Airport | 5,200 | June 2 | September 13 | 101 |
| Dillon U of Montana Western | 5,130 | June 5 | September 13 | 98 |
| Divide | 5,350 | June 10 | September 7 | 85 |
| Drummond Aviation | 4,000 | Frost possible any month | 80 | |
| Dunkirk 19 NNE | 3,320 | May 23 | September 14 | 112 |
| E Glacier | 4,810 | June 8 | September 5 | 88 |
| Ekalaka | 3,430 | May 20 | September 23 | 126 |
| Elliston | 5,080 | June 9 | September 8 | 91 |
| Ennis | 4,950 | June 16 | September 4 | 78 |
| Eureka RS | 2,530 | May 11 | September 27 | 138 |
| Fairfield | 3,980 | May 13 | September 27 | 135 |
| Flatwillow 4 ENE | 3,290 | May 16 | September 28 | 132 |
| Forsyth | 2,520 | May 9 | September 29 | 142 |
| Fort Assiniboine | 2,670 | May 15 | September 24 | 130 |
| Fort Belknap 2 SW | 2,530 | May 16 | September 22 | 128 |
| Fort Benton | 2,650 | May 15 | September 22 | 129 |
| Fort Peck Power Plant | 2,070 | May 8 | October 1 | 145 |
| Fortine 1 N | 3,000 | May 16 | September 18 | 121 |
| Gardiner | 5,280 | May 21 | September 27 | 128 |
| Geraldine | 3,150 | May 14 | September 26 | 134 |
| Gibson 2 NE | 4,450 | May 27 | September 18 | 113 |
| Gibson Dam | 4,590 | June 12 | September 8 | 88 |
| Gildford | 2,820 | May 24 | September 15 | 114 |
| Glasgow #2 | 2,090 | May 3 | October 1 | 151 |
| Glasgow International Airport | 2,290 | May 6 | September 30 | 145 |
| Glen 4 N | 5,060 | Frost possible any month | 71 | |
| Glendive | 2,080 | May 3 | October 4 | 153 |
| Goldbutte 7 N | 3,500 | Frost possible any month | 77 | |
| Grass Range | 3,490 | May 20 | September 24 | 126 |
| Great Falls 16st | 3,500 | May 6 | October 1 | 147 |
| Great Falls International Airport | 3,660 | May 19 | September 24 | 126 |
| Great Falls WFO | 3,700 | May 12 | September 28 | 138 |
| Hamilton | 3,590 | May 21 | September 22 | 122 |
| Hardin | 2,880 | May 13 | September 29 | 135 |
| Harlem | 2,370 | May 16 | September 21 | 125 |
| Harlem 20 S | 2,690 | May 24 | September 22 | 118 |
| Harlowton | 4,220 | May 23 | September 16 | 113 |
| Harlowton 11 NW | 4,950 | May 30 | September 20 | 110 |
| Haugan 1 W | 3,160 | Frost possible any month | 90 | |
| Havre City Co Airport | 2,590 | May 15 | September 23 | 129 |
| Hebgen Dam | 6,490 | June 15 | September 10 | 87 |
| Helena Regional Airport | 3,830 | May 9 | September 30 | 142 |
| Heron 2 NW | 2,240 | May 20 | September 20 | 119 |
| Highwood 7 NE | 3,600 | May 7 | October 2 | 149 |
| Hinsdale 4 SW | 2,810 | May 15 | September 26 | 132 |
| Holter Dam | 3,490 | May 19 | September 24 | 124 |
| Hungry Horse Dam | 3,160 | May 9 | October 1 | 141 |
| Huntley Exp Station | 3,030 | May 12 | September 25 | 136 |
| Hysham | 2,670 | May 10 | September 29 | 141 |
| Hysham 25 SSE | 3,100 | May 26 | September 16 | 111 |
| Ingomar 9 E | 2,800 | May 21 | September 19 | 120 |
| Jackson | 6,480 | Frost possible any month | 51 | |
| Joliet | 3,840 | May 29 | September 15 | 107 |
| Joplin | 3,320 | May 21 | September 19 | 119 |
| Jordan | 2,620 | May 21 | September 18 | 118 |
| Jordan Airport | 2,660 | May 18 | September 20 | 123 |
| Judith Gap | 4,630 | June 1 | September 15 | 104 |
| Judith Gap 13 E | 4,790 | June 3 | September 15 | 100 |
| Kalispell Glacier Airport | 2,960 | May 31 | September 10 | 100 |
| Lakeview | 6,710 | Frost possible any month | 66 | |
| Laurin 2 NE | 5,200 | May 24 | September 22 | 117 |
| Lennep 5 SW | 5,600 | Frost possible any month | 65 | |
| Lewistown | 3,910 | May 14 | September 28 | 135 |
| Lewistown 11 ESE | 5,030 | May 19 | September 25 | 128 |
| Lewistown 11 SSE | 4,960 | May 31 | September 14 | 105 |
| Lewistown 42 WSW | 5,070 | June 15 | September 4 | 77 |
| Lewistown Municipal Airport | 4,140 | May 23 | September 21 | 119 |
| Libby | 2,140 | May 10 | September 26 | 137 |
| Libby 1 NE RS | 2,100 | May 23 | September 21 | 120 |
| Libby 32 SSE | 3,440 | Frost possible any month | 44 | |
| Libby Dam (base) | 2,110 | May 11 | October 1 | 142 |
| Lima | 6,280 | June 11 | September 10 | 89 |
| Lincoln RS | 4,580 | Frost possible any month | 65 | |
| Lindbergh Lake | 4,320 | May 20 | September 22 | 120 |
| Livingston 12 S | 5,040 | May 19 | September 25 | 125 |
| Livingston Mission Field | 4,640 | May 27 | September 14 | 108 |
| Logan Landfill | 4,240 | May 26 | September 15 | 111 |
| Loma | 2,580 | May 20 | September 19 | 120 |
| Malta | 2,260 | May 10 | September 29 | 139 |
| Malta 35 S | 2,610 | May 16 | September 23 | 128 |
| Malta 7 E | 2,230 | May 7 | September 28 | 143 |
| Martinsdale 3 NNW | 4,800 | June 3 | September 8 | 94 |
| Medicine Lake 3 SE | 1,940 | May 16 | September 18 | 125 |
| Melstone | 2,930 | May 10 | September 29 | 141 |
| Melville 4 W | 5,360 | June 9 | September 7 | 88 |
| Mildred 5 N | 2,480 | May 20 | September 22 | 124 |
| Miles City F Wiley Field | 2,620 | May 8 | September 30 | 144 |
| Millegan 14 SE | 4,970 | June 11 | September 6 | 86 |
| Missoula 2 NE | 3,420 | May 10 | October 1 | 143 |
| Missoula 6 NW WFO | 3,200 | May 6 | October 4 | 151 |
| Missoula International Airport | 3,190 | May 16 | September 26 | 130 |
| Mizpah 4 NNW | 2,480 | May 22 | September 15 | 117 |
| Moccasin Exp Station | 4,300 | May 28 | September 20 | 112 |
| Moorhead 9 NE | 3,220 | May 17 | September 22 | 126 |
| Mosby 4 ENE | 2,910 | May 5 | October 4 | 151 |
| Mystic Lake | 6,550 | June 5 | September 14 | 99 |
| Nashua #2 | 2,070 | May 12 | September 24 | 134 |
| Neihart 8 NNW | 5,230 | June 6 | September 12 | 99 |
| Norris Madison Power House | 4,740 | April 30 | October 10 | 162 |
| Nye #2 | 4,840 | June 1 | September 11 | 100 |
| Olney | 3,170 | Frost possible any month | 60 | |
| Opheim 10 N | 2,880 | June 1 | September 7 | 99 |
| Opheim 12 SSE | 2,940 | June 5 | September 2 | 89 |
| Ovando 9 SSE | 4,320 | Frost possible any month | 67 | |
| Phillipsburg RS | 5,270 | Frost possible any month | 65 | |
| Plentywood | 2,050 | May 25 | September 14 | 111 |
| Plevna | 2,780 | May 21 | September 20 | 121 |
| Polebridge | 3,520 | Frost possible any month | 40 | |
| Polson | 3,010 | May 10 | October 5 | 147 |
| Pompeys Pillar 15 N | 3,390 | May 22 | September 22 | 121 |
| Port of Morgan | 2,830 | May 19 | September 22 | 124 |
| Potomac | 3,690 | Frost possible any month | 45 | |
| Powderville 8 NNE | 2,800 | May 13 | September 25 | 132 |
| Rapelje | 4,070 | May 24 | September 21 | 116 |
| Raymond Border Station | 2,350 | May 19 | September 23 | 125 |
| Raynesford 2 NNW | 4,220 | May 22 | September 23 | 123 |
| Red Lodge | 5,650 | June 3 | September 19 | 106 |
| Redstone | 2,110 | May 28 | September 7 | 101 |
| Ridgeway 1 S | 3,320 | May 17 | September 22 | 127 |
| Rock Springs | 3,020 | May 15 | September 25 | 132 |
| Rogers Pass 9 NNE | 4,200 | May 21 | September 15 | 115 |
| Roundup | 3,200 | May 20 | September 21 | 124 |
| Roundup 15 SW | 3,390 | May 22 | September 15 | 114 |
| Roy 8 NE | 3,080 | May 14 | September 24 | 134 |
| Rudyard 19 S | 2,880 | May 23 | September 19 | 119 |
| Rudyard 21 N | 3,000 | May 30 | September 11 | 103 |
| Ryegate | 3,650 | May 17 | September 23 | 127 |
| Ryegate 18 NNW | 4,440 | May 26 | September 18 | 112 |
| Saco 1 NNW | 2,190 | May 15 | September 23 | 130 |
| Saint Ignatius | 2,920 | May 12 | October 2 | 142 |
| Saint Regis 1 NE | 2,660 | Frost possible any month | 101 | |
| Sand Creek | 2,910 | May 12 | September 27 | 136 |
| Savage | 1,980 | May 12 | September 25 | 135 |
| Scobey 4 NW | 2,390 | May 28 | September 6 | 99 |
| Seeley Lake RS | 4,100 | Frost possible any month | 74 | |
| Shelby | 3,330 | May 23 | September 16 | 115 |
| Shonkin 7 S | 4,300 | May 24 | September 21 | 119 |
| Sidney | 1,930 | May 11 | September 27 | 137 |
| Silver Gate | 7,500 | Frost possible any month | 31 | |
| Simpson 6 N - Wildhorse | 2,810 | May 26 | September 15 | 110 |
| SKQ Dam | 2,730 | May 15 | September 28 | 134 |
| Sonnette 7 SW | 3,910 | May 25 | September 19 | 115 |
| St Marie | 2,760 | May 13 | September 27 | 134 |
| St Mary | 4,560 | June 12 | September 5 | 82 |
| St. Mary 1 SSW | 4,550 | June 3 | September 8 | 94 |
| Stanford | 4,860 | May 25 | September 21 | 118 |
| Stevensville | 3,380 | May 22 | September 19 | 115 |
| Sula 14 NE | 5,150 | Frost possible any month | 39 | |
| Sula 3 ENE | 4,480 | Frost possible any month | 59 | |
| Sun River 4 S | 3,600 | June 2 | September 10 | 96 |
| Sunburst 8 E | 3,700 | May 17 | September 25 | 129 |
| Superior | 2,710 | May 17 | September 23 | 125 |
| Swan Lake | 3,100 | May 17 | September 19 | 121 |
| Sweetgrass | 3,510 | May 15 | September 25 | 132 |
| Terry | 2,250 | May 12 | September 28 | 137 |
| Terry 21 NNW | 3,140 | May 26 | September 17 | 113 |
| Thompson Falls PH | 2,380 | May 7 | October 4 | 150 |
| Tiber Dam | 2,850 | May 16 | September 23 | 129 |
| Tizer Gardens | 4,670 | June 18 | September 5 | 81 |
| Townsend 3 SE | 3,960 | May 19 | September 19 | 122 |
| Trident | 4,040 | May 9 | September 27 | 139 |
| Trout Creek RS | 2,360 | May 20 | September 21 | 122 |
| Troy | 1,930 | May 14 | September 25 | 132 |
| Turner 11 N | 2,980 | May 19 | September 21 | 124 |
| Twin Bridges | 4,630 | June 8 | September 2 | 82 |
| Valentine | 2,900 | May 18 | September 21 | 124 |
| Valier | 3,810 | May 17 | September 24 | 129 |
| Vida 6 NE | 2,280 | May 16 | September 22 | 129 |
| Virginia City | 5,770 | June 4 | September 18 | 106 |
| W Glacier | 3,150 | May 18 | September 20 | 124 |
| W Yellowstone Gateway | 6,680 | Frost possible any month | 33 | |
| Westby | 2,100 | May 18 | September 21 | 125 |
| Western Ag Research Center | 3,610 | May 23 | September 21 | 118 |
| White Sulphur Springs #2 | 5,040 | June 4 | September 11 | 97 |
| Whitefish | 3,100 | May 16 | September 25 | 129 |
| Wibaux 2 E | 2,700 | May 27 | September 16 | 112 |
| Wilsall 1 S | 5,020 | June 4 | September 6 | 92 |
| Wilsall 8 ENE | 5,870 | June 8 | September 7 | 89 |
| Winifred | 3,240 | May 16 | September 23 | 127 |
| Wisdom | 6,060 | Frost possible any month | 22 | |
| Wise River 3 WNW | 5,730 | Frost possible any month | 27 | |
| Wolf Point | 2,090 | May 8 | September 28 | 143 |
| Wolf Point 29 ENE | 2,090 | May 24 | September 14 | 110 |
| Wolf Point 34 NE | 2,640 | May 13 | September 28 | 137 |
| Wolf Point International Airport | 1,980 | May 16 | September 20 | 125 |
| Wyola 1 SW | 3,730 | May 21 | September 17 | 117 |
| Yaak 9 NNE | 3,080 | Frost possible any month | 74 | |
| Yellowtail Dam | 3,300 | May 7 | October 5 | 151 |
| Zortman | 4,040 | May 18 | September 23 | 126 |
Typical (1-in-2) dates at 32°F. For the early and late years, and a planting calendar built from your own dates, look up your ZIP code.