Checking current alerts… View NWS forecast and alerts.
Will it freeze in Great Falls in the next 7 nights?
No overnight lows at or below 32°F are forecast in Great Falls during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 35°F. Frost possible.
NWS forecast period: Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST.
1 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 35°F Frost possible · Mostly Clear
- Fri, Nov 6 45°F Above 36°F · Partly Cloudy
- Sat, Nov 7 43°F Above 36°F · Partly Cloudy
- Sun, Nov 8 37°F Above 36°F · Partly Cloudy
- Mon, Nov 9 40°F Above 36°F · Partly Cloudy
- Tue, Nov 10 43°F Above 36°F · Partly Cloudy
- Wed, Nov 11 44°F Above 36°F · Partly Cloudy
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Great Falls
The median first fall hard-freeze date (28°F) is October 11, from NOAA’s 1991–2020 Climate Normals at Great Falls 16ST. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | May 6 · May 19 · Jun 1 | Sep 7 · Sep 21 · Oct 3 | 124 days |
| 32°F freeze | Apr 23 · May 6 · May 19 | Sep 17 · Oct 1 · Oct 16 | 147 days |
| 28°F hard freeze | Apr 7 · Apr 24 · May 8 | Sep 25 · Oct 11 · Oct 29 | 171 days |
Average high temperature by month
1991–2020 normals at Great Falls 16ST
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Great Falls, MT come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Great Falls 16ST (station USC00243749, elevation 3,505 ft), 1.4 mi from Great Falls. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Great Falls
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Helena, MT | 71 mi | May 9 | Sep 30 |
| Lewistown, MT | 92 mi | May 23 | Sep 21 |
| Havre, MT | 104 mi | May 15 | Sep 23 |
| Belgrade, MT | 119 mi | May 26 | Sep 16 |
| Bozeman, MT | 126 mi | May 26 | Sep 22 |
| Butte, MT | 129 mi | Jun 13 | Sep 5 |
| Anaconda, MT | 130 mi | Jun 1 | Sep 14 |
| Livingston, MT | 132 mi | May 27 | Sep 14 |
| Polson, MT | 133 mi | May 10 | Oct 5 |
| Missoula, MT | 135 mi | May 10 | Oct 1 |
Frequently asked questions
When is the last frost in Great Falls?
On average, the last spring frost (32°F) in Great Falls is around May 6. In about 1 year in 10 it comes after May 19, and in 9 years in 10 it comes after April 23.
When is the first frost in Great Falls?
The first fall frost (32°F) usually arrives around October 1. There’s a 10% chance of a freeze by September 17 and a 90% chance by October 16.
Can it frost in Great Falls after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after May 19.
What growing zone is Great Falls?
Great Falls is in USDA Plant Hardiness Zone 4b (average annual extreme minimum temperature −25 to −20°F), based on the 2023 USDA map for ZIP code 59401. See growing zones in Montana.
More: all Montana frost dates · Montana growing zones · UV index today in Great Falls · frost vs. freeze