Last frost date in Great Falls, Montana
May 6
Average last frost in spring. In an early year (1 in 10) it's over by April 23; in a late year (1 in 10) it comes after May 19.
October 1
Average first frost in fall. 1 year in 10 it comes by September 17.
Source: NOAA U.S. Climate Normals 1991–2020, station Great Falls 16st (USC00243749), 1.4 miles from Great Falls, elevation 3,505 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.
| Early year | Average | Late year | |
|---|---|---|---|
| Last frost in spring | Apr 23 | May 6 | May 19 |
| First frost in fall | Sept 17 | Oct 1 | Oct 16 |
Frost-free days in an average year: 147
| Chance in a year | Average last in spring | Average first in fall | |
|---|---|---|---|
| Light frost (36°F) | Every year | May 19 | Sept 21 |
| Frost (32°F) | Every year | May 6 | Oct 1 |
| Hard freeze (28°F) | Every year | Apr 24 | Oct 11 |
Nights at 32°F or colder in an average year: 143
What to plant now in Great Falls
- Spring planting calendar for an average last frost around May 10 Great Falls: May 6
- Fall planting calendar for an average first frost around September 30 Great Falls: October 1
Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5. How we match the table.
Nearby in Montana
- Helena 71 mi · last frost May 9
- Belgrade 119 mi · last frost May 26
- Bozeman 126 mi · last frost May 26
- Butte-Silver Bow (balance) 128 mi · last frost June 13
- Missoula 135 mi · last frost May 10
Updated