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Will it freeze in Sidney in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 25°F (Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST).
Tonight: forecast low 25°F. Hard freeze.
NWS forecast period: Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST.
6 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 25°F Hard freeze · Partly Cloudy
- Fri, Nov 6 33°F Frost possible · Partly Cloudy
- Sat, Nov 7 31°F Freeze · Mostly Clear
- Sun, Nov 8 38°F Above 36°F · Partly Cloudy
- Mon, Nov 9 30°F Freeze · Mostly Cloudy
- Tue, Nov 10 36°F Frost possible · Partly Cloudy
- Wed, Nov 11 36°F Frost possible · 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 Sidney
The median first fall hard-freeze date (28°F) is October 6, from NOAA’s 1991–2020 Climate Normals at Sidney. 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 9 · May 21 · Jun 3 | Sep 4 · Sep 18 · Sep 30 | 118 days |
| 32°F freeze | Apr 30 · May 11 · May 25 | Sep 13 · Sep 27 · Oct 9 | 137 days |
| 28°F hard freeze | Apr 18 · May 2 · May 16 | Sep 22 · Oct 6 · Oct 20 | 155 days |
Average high temperature by month
1991–2020 normals at Sidney
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 Sidney, MT come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Sidney (station USC00247560, elevation 1,933 ft), 1.3 mi from Sidney. 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 Sidney
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Williston, ND | 40 mi | May 21 | Sep 21 |
| Watford City, ND | 42 mi | May 9 | Sep 27 |
| Dickinson, ND | 86 mi | May 20 | Sep 22 |
| Miles City, MT | 120 mi | May 8 | Sep 30 |
| Minot, ND | 139 mi | May 10 | Oct 1 |
| Belle Fourche, SD | 211 mi | May 10 | Sep 30 |
| Sheridan, WY | 242 mi | May 21 | Sep 23 |
Frequently asked questions
When is the last frost in Sidney?
On average, the last spring frost (32°F) in Sidney is around May 11. In about 1 year in 10 it comes after May 25, and in 9 years in 10 it comes after April 30.
When is the first frost in Sidney?
The first fall frost (32°F) usually arrives around September 27. There’s a 10% chance of a freeze by September 13 and a 90% chance by October 9.
Can it frost in Sidney 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 21.
What growing zone is Sidney?
Sidney is in USDA Plant Hardiness Zone 4a (average annual extreme minimum temperature −30 to −25°F), based on the 2023 USDA map for ZIP code 59270. See growing zones in Montana.
More: all Montana frost dates · Montana growing zones · frost vs. freeze