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Will it freeze in Ammon 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 · Areas Of Fog
- Fri, Nov 6 31°F Freeze · Partly Cloudy
- Sat, Nov 7 33°F Frost possible · Mostly Clear
- Sun, Nov 8 36°F Frost possible · Partly Cloudy
- Mon, Nov 9 39°F Above 36°F · Mostly Cloudy
- Tue, Nov 10 37°F Above 36°F · Mostly Clear
- Wed, Nov 11 39°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 Ammon
The median first fall hard-freeze date (28°F) is October 13, from NOAA’s 1991–2020 Climate Normals at Idaho Falls - Kifi. 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 10 · May 30 · Jun 16 | Sep 4 · Sep 20 · Oct 3 | 113 days |
| 32°F freeze | Apr 27 · May 9 · Jun 2 | Sep 17 · Oct 1 · Oct 15 | 142 days |
| 28°F hard freeze | Apr 11 · Apr 28 · May 11 | Sep 27 · Oct 13 · Oct 27 | 168 days |
Average high temperature by month
1991–2020 normals at Idaho Falls - Kifi
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 Ammon, ID come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Idaho Falls - Kifi (station USC00104455, elevation 4,742 ft), 3.8 mi from Ammon. 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 Ammon
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Idaho Falls, ID | 3.7 mi | May 9 | Oct 1 |
| Shelley, ID | 11 mi | May 23 | Sep 20 |
| Rigby, ID | 14 mi | May 9 | Oct 5 |
| Rexburg, ID | 25 mi | May 12 | Sep 24 |
| Blackfoot, ID | 27 mi | May 5 | Oct 3 |
| Chubbuck, ID | 45 mi | May 16 | Oct 2 |
| Pocatello, ID | 49 mi | May 2 | Oct 11 |
| Jackson, WY | 60 mi | Jun 20 | Aug 31 |
| Preston, ID | 95 mi | May 16 | Sep 28 |
| Rupert, ID | 105 mi | May 6 | Oct 6 |
Frequently asked questions
When is the last frost in Ammon?
On average, the last spring frost (32°F) in Ammon is around May 9. In about 1 year in 10 it comes after June 2, and in 9 years in 10 it comes after April 27.
When is the first frost in Ammon?
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 15.
Can it frost in Ammon 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 30.
What growing zone is Ammon?
Ammon is in USDA Plant Hardiness Zone 5b (average annual extreme minimum temperature −15 to −10°F), based on the 2023 USDA map for ZIP code 83406. See growing zones in Idaho.
More: all Idaho frost dates · Idaho growing zones · frost vs. freeze