Frost dates by state › Montana
Montana frost dates
Average last spring and first fall frost dates for Montana’s largest cities, with each city’s USDA hardiness zone.
Reviewed October 2026
Among Montana’s 20 largest cities, the average last spring frost ranges from May 3 in Glendive to Jun 13 in Butte. Elevation, distance from the coast and city heat all shift the date, so use your own ZIP code below for the closest match.
| City | Average last spring frost | Average first fall frost | Frost-free days | Hardiness zone | Weather station used |
|---|---|---|---|---|---|
| Billings | May 4 | Oct 7 | 156 | 5a | Billings Logan Intl Airport, MT |
| Missoula | May 10 | Oct 1 | 144 | 5b | Missoula 2 Ne, MT, 3 mi |
| Great Falls | May 6 | Oct 1 | 148 | 4b | Great Falls 16St, MT |
| Bozeman | May 26 | Sep 22 | 119 | 5a | Bozeman Montana State Univ, MT |
| Butte | Jun 13 | Sep 5 | 84 | 5a | Butte Bert Mooney Airport, MT, 9 mi |
| Helena | May 9 | Sep 30 | 144 | 4b–5a | Helena Rgnl Airport, MT, 3 mi |
| Kalispell | May 31 | Sep 10 | 102 | 5b | Kalispell Glacier Airport, MT, 7 mi |
| Belgrade | May 26 | Sep 16 | 113 | 5a | Bozeman Gallatin Fld, MT |
| Anaconda | Jun 1 | Sep 14 | 105 | 5a | Anaconda, MT, 10 mi |
| Whitefish | May 16 | Sep 25 | 132 | 5a | Whitefish, MT, 2 mi |
| Havre | May 15 | Sep 23 | 131 | 3b | Havre City Co Airport, MT, 4 mi |
| Livingston | May 27 | Sep 14 | 110 | 5a | Livingston Mission Fld, MT, 6 mi |
| Miles City | May 8 | Sep 30 | 145 | 4b | Miles City F Wiley Fld, MT, 3 mi |
| Laurel | May 5 | Oct 3 | 151 | 5a | Billings Wfo, MT, 11 mi |
| Lewistown | May 23 | Sep 21 | 121 | 4b | Lewistown Muni Airport, MT |
| Sidney | May 11 | Sep 27 | 139 | 4a | Sidney, MT |
| Columbia Falls | May 31 | Sep 10 | 102 | 5a | Kalispell Glacier Airport, MT, 6 mi |
| Polson | May 10 | Oct 5 | 148 | 6a | Polson, MT, 2 mi |
| Hamilton | May 21 | Sep 22 | 124 | 5b | Hamilton, MT |
| Glendive | May 3 | Oct 4 | 154 | 4a | Glendive, MT |
Frost dates are the dates after (spring) or before (fall) which the chance of a 32°F freeze is below 50%, from NOAA’s 1991–2020 U.S. Climate Normals for the weather station nearest each city’s center. Zones are from the 2023 USDA Plant Hardiness Zone Map for the ZIP codes around each city; a range means nearby ZIP codes differ. Cities are the 20 largest by Census Bureau 2024 population estimates.
An average is not a guarantee. There’s still about a 1 in 2 chance of frost after the average last spring date. Many gardeners wait an extra week or two before setting out tomatoes, peppers and basil, and keep covers handy.
Planting dates for Billings
Timed from Billings’s average last frost of May 4, using University of New Hampshire Extension’s planting guidance. For your exact dates, enter your ZIP code in the calendar below.
| Crop | Start seeds indoors | Plant outside |
|---|---|---|
| Tomatoes | Mar 16 to Mar 30 | May 11 to May 18 |
| Peppers | Mar 9 to Mar 23 | May 18 |
| Lettuce | Mar 2 to Mar 9 | Apr 6 to Apr 13 |
| Broccoli | Feb 23 to Mar 9 | Apr 6 to Apr 20 |
| Cucumbers | Apr 13 to Apr 20 | May 11 to May 18 |
| Basil | Mar 23 to Apr 6 | May 18 |
When to plant, for your garden
Your seed-starting and planting dates, timed from your last spring frost. Full calendar, 12 crops.
Enter your ZIP code to look up your average last frost date and hardiness zone, or type the date in yourself.
Frost dates: NOAA U.S. Climate Normals, 1991–2020. Hardiness zones: USDA Plant Hardiness Zone Map, 2023, ZIP code data from PRISM Group, Oregon State University, prism.oregonstate.edu, accessed Oct. 20, 2026.
More about frost dates
How to find your last frost date, and what your zone means · Full planting calendar · How to start seeds indoors
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