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Will it freeze in Lewistown in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 31°F (Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST).
Tonight: forecast low 31°F. Freeze.
NWS forecast period: Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST.
3 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 31°F Freeze · Partly Cloudy
- Fri, Nov 6 37°F Above 36°F · Partly Cloudy
- Sat, Nov 7 40°F Above 36°F · Partly Cloudy
- Sun, Nov 8 35°F Frost possible · Mostly Cloudy
- Mon, Nov 9 36°F Frost possible · Mostly Cloudy
- Tue, Nov 10 39°F Above 36°F · Partly Cloudy
- Wed, Nov 11 41°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 Lewistown
The median first fall hard-freeze date (28°F) is October 1, from NOAA’s 1991–2020 Climate Normals at Lewistown Municipal Airport. 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 26 · Jun 11 · Jul 3 | Aug 24 · Sep 8 · Sep 21 | 86 days |
| 32°F freeze | May 11 · May 23 · Jun 8 | Sep 8 · Sep 21 · Oct 3 | 119 days |
| 28°F hard freeze | Apr 27 · May 9 · May 24 | Sep 18 · Oct 1 · Oct 15 | 145 days |
Average high temperature by month
1991–2020 normals at Lewistown Municipal Airport
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 Lewistown, MT come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Lewistown Municipal Airport (station USW00024036, elevation 4,145 ft), 0.3 mi from Lewistown. 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 Lewistown
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Great Falls, MT | 92 mi | May 6 | Oct 1 |
| Billings, MT | 97 mi | May 4 | Oct 7 |
| Laurel, MT | 101 mi | May 5 | Oct 3 |
| Havre, MT | 104 mi | May 15 | Sep 23 |
| Livingston, MT | 109 mi | May 27 | Sep 14 |
| Belgrade, MT | 120 mi | May 26 | Sep 16 |
| Bozeman, MT | 122 mi | May 26 | Sep 22 |
| Helena, MT | 126 mi | May 9 | Sep 30 |
| Powell, WY | 162 mi | May 19 | Sep 20 |
| Cody, WY | 176 mi | May 12 | Oct 1 |
Frequently asked questions
When is the last frost in Lewistown?
On average, the last spring frost (32°F) in Lewistown is around May 23. In about 1 year in 10 it comes after June 8, and in 9 years in 10 it comes after May 11.
When is the first frost in Lewistown?
The first fall frost (32°F) usually arrives around September 21. There’s a 10% chance of a freeze by September 8 and a 90% chance by October 3.
Can it frost in Lewistown 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 June 11.
What growing zone is Lewistown?
Lewistown 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 59457. See growing zones in Montana.
More: all Montana frost dates · Montana growing zones · frost vs. freeze