Last frost date in Idaho Falls, Idaho
May 9
Average last frost in spring. In an early year (1 in 10) it's over by April 27; in a late year (1 in 10) it comes after June 2.
October 1
Average first frost in fall. 1 year in 10 it comes by September 17.
Source: NOAA U.S. Climate Normals 1991–2020, station Idaho Falls - Kifi (USC00104455), 2 miles from Idaho Falls, elevation 4,742 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.
This station is also the nearest one for Ammon, so its frost dates are the same as Idaho Falls's.
| Early year | Average | Late year | |
|---|---|---|---|
| Last frost in spring | Apr 27 | May 9 | June 2 |
| First frost in fall | Sept 17 | Oct 1 | Oct 15 |
Frost-free days in an average year: 142
| Chance in a year | Average last in spring | Average first in fall | |
|---|---|---|---|
| Light frost (36°F) | Every year | May 30 | Sept 20 |
| Frost (32°F) | Every year | May 9 | Oct 1 |
| Hard freeze (28°F) | Every year | Apr 28 | Oct 13 |
Nights at 32°F or colder in an average year: 166
What to plant now in Idaho Falls
- Spring planting calendar for an average last frost around May 10 Idaho Falls: May 9
- Fall planting calendar for an average first frost around September 30 Idaho Falls: October 1
Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5. How we match the table.
Nearby in Idaho
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