Last spring frost
May 24
Frost Dates for Nezperce, ID
First fall frost
Sep 20
Growing season
116 days
Hardiness zone
6b
In an average year around Nezperce, ID, the last spring frost (32°F) is about May 24 and the first fall frost is about Sep 20, giving roughly a 116-day growing season. To be safe most years, wait until May 6 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Freeze (32°F) | Jun 19 | May 24 | May 6 |
| Hard (28°F) | May 25 | May 5 | Apr 19 |
| Severe (24°F) | May 8 | Apr 16 | Mar 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 19 | Jun 10 | Jun 3 | May 29 | May 24 | May 20 | May 16 | May 12 | May 6 |
| 28°F | May 25 | May 17 | May 12 | May 9 | May 5 | May 3 | Apr 30 | Apr 26 | Apr 19 |
| 24°F | May 8 | May 2 | Apr 27 | Apr 22 | Apr 16 | Apr 10 | Apr 5 | Mar 30 | Mar 22 |
| 20°F | Apr 16 | Apr 5 | Mar 31 | Mar 26 | Mar 21 | Mar 15 | Mar 10 | Mar 6 | Feb 28 |
| 16°F | Mar 26 | Mar 17 | Mar 12 | Mar 7 | Mar 3 | Feb 28 | Feb 23 | Feb 17 | Feb 8 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Freeze (32°F) | Sep 1 | Sep 20 | Oct 5 |
| Hard (28°F) | Sep 13 | Oct 2 | Oct 19 |
| Severe (24°F) | Sep 28 | Oct 16 | Nov 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Sep 1 | Sep 7 | Sep 12 | Sep 16 | Sep 20 | Sep 23 | Sep 26 | Sep 30 | Oct 5 |
| 28°F | Sep 13 | Sep 21 | Sep 25 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 13 | Oct 19 |
| 24°F | Sep 28 | Oct 2 | Oct 7 | Oct 12 | Oct 16 | Oct 21 | Oct 25 | Oct 30 | Nov 5 |
| 20°F | Oct 10 | Oct 18 | Oct 24 | Oct 29 | Nov 2 | Nov 8 | Nov 13 | Nov 19 | Nov 25 |
| 16°F | Oct 22 | Oct 31 | Nov 6 | Nov 12 | Nov 17 | Nov 21 | Nov 25 | Nov 29 | Dec 8 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Nezperce, Id, about 2.9 miles away@if(!empty($station['elevation_ft'])), at 3,248 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Nezperce, ID?
On average, the last spring frost (32°F) around Nezperce, ID is about May 24. In cooler years it can run later, so for a safer bet many gardeners wait until May 6.
When is the first frost in the fall?
The first fall frost around Nezperce, ID typically arrives about Sep 20. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around May 24 on average, or May 6 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 116 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 83543 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026