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Will it freeze in Casper in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 32°F (Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST).
Tonight: forecast low 32°F. Freeze.
NWS forecast period: Thu, Nov 5, 6:00 PM MST to Fri, Nov 6, 6:00 AM MST.
4 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 32°F Freeze · Mostly Cloudy
- Fri, Nov 6 31°F Freeze · Clear
- Sat, Nov 7 33°F Frost possible · Mostly Clear
- Sun, Nov 8 38°F Above 36°F · Mostly Clear
- Mon, Nov 9 38°F Above 36°F · Partly Cloudy
- Tue, Nov 10 36°F Frost possible · Mostly Clear
- Wed, Nov 11 39°F Above 36°F · Mostly Clear
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 Casper
The median first fall hard-freeze date (28°F) is October 6, from NOAA’s 1991–2020 Climate Normals at Casper Wastewater Plant. 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 11 · May 23 · Jun 6 | Sep 6 · Sep 19 · Oct 2 | 116 days |
| 32°F freeze | Apr 30 · May 10 · May 24 | Sep 14 · Sep 29 · Oct 12 | 138 days |
| 28°F hard freeze | Apr 17 · May 1 · May 14 | Sep 21 · Oct 6 · Oct 23 | 156 days |
Average high temperature by month
1991–2020 normals at Casper Wastewater Plant
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 Casper, WY come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Casper Wastewater Plant (station USC00481569, elevation 5,097 ft), 2.0 mi from Casper. 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 Casper
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Douglas, WY | 47 mi | May 19 | Sep 23 |
| Rawlins, WY | 86 mi | May 17 | Oct 2 |
| Riverton, WY | 105 mi | May 12 | Sep 24 |
| Gillette, WY | 107 mi | May 15 | Oct 1 |
| Laramie, WY | 112 mi | Jun 7 | Sep 4 |
| Torrington, WY | 122 mi | May 11 | Sep 29 |
| Lander, WY | 122 mi | May 18 | Sep 27 |
| Sheridan, WY | 139 mi | May 21 | Sep 23 |
| Cheyenne, WY | 142 mi | May 14 | Oct 1 |
| Scottsbluff, NE | 152 mi | May 8 | Oct 3 |
Frequently asked questions
When is the last frost in Casper?
On average, the last spring frost (32°F) in Casper is around May 10. In about 1 year in 10 it comes after May 24, and in 9 years in 10 it comes after April 30.
When is the first frost in Casper?
The first fall frost (32°F) usually arrives around September 29. There’s a 10% chance of a freeze by September 14 and a 90% chance by October 12.
Can it frost in Casper 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 23.
What growing zone is Casper?
Casper is in USDA Plant Hardiness Zone 5a (average annual extreme minimum temperature −20 to −15°F), based on the 2023 USDA map for ZIP code 82644. See growing zones in Wyoming.
More: all Wyoming frost dates · Wyoming growing zones · UV index today in Casper · frost vs. freeze