Last spring frost
Apr 6
Frost Dates for Asotin, ID
First fall frost
Oct 26
Growing season
200 days
Hardiness zone
7b
In an average year around Asotin, ID, the last spring frost (32°F) is about Apr 6 and the first fall frost is about Oct 26, giving roughly a 200-day growing season. To be safe most years, wait until Mar 20 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%) |
|---|---|---|---|
| Light (36°F) | May 12 | Apr 29 | Apr 11 |
| Freeze (32°F) | Apr 26 | Apr 6 | Mar 20 |
| Hard (28°F) | Apr 4 | Mar 15 | Feb 25 |
| Severe (24°F) | Mar 19 | Feb 27 | Jan 27 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 12 | May 7 | May 3 | May 1 | Apr 29 | Apr 25 | Apr 21 | Apr 17 | Apr 11 |
| 32°F | Apr 26 | Apr 19 | Apr 14 | Apr 10 | Apr 6 | Apr 3 | Mar 31 | Mar 27 | Mar 20 |
| 28°F | Apr 4 | Mar 30 | Mar 26 | Mar 20 | Mar 15 | Mar 11 | Mar 6 | Mar 2 | Feb 25 |
| 24°F | Mar 19 | Mar 10 | Mar 5 | Mar 1 | Feb 27 | Feb 22 | Feb 16 | Feb 8 | Jan 27 |
| 20°F | Mar 5 | Feb 28 | Feb 22 | Feb 16 | Feb 9 | Feb 1 | Jan 24 | Jan 13 | Jan 1 |
| 16°F | Feb 27 | Feb 17 | Feb 8 | Jan 31 | Jan 23 | Jan 13 | Jan 4 | Dec 28 | Dec 12 |
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%) |
|---|---|---|---|
| Light (36°F) | Oct 1 | Oct 13 | Oct 28 |
| Freeze (32°F) | Oct 10 | Oct 26 | Nov 12 |
| Hard (28°F) | Oct 20 | Nov 8 | Nov 28 |
| Severe (24°F) | Oct 30 | Nov 23 | Dec 13 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 5 | Oct 7 | Oct 10 | Oct 13 | Oct 15 | Oct 18 | Oct 23 | Oct 28 |
| 32°F | Oct 10 | Oct 14 | Oct 18 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 5 | Nov 12 |
| 28°F | Oct 20 | Oct 27 | Nov 1 | Nov 4 | Nov 8 | Nov 13 | Nov 18 | Nov 23 | Nov 28 |
| 24°F | Oct 30 | Nov 7 | Nov 13 | Nov 19 | Nov 23 | Nov 26 | Nov 30 | Dec 6 | Dec 13 |
| 20°F | Nov 10 | Nov 20 | Nov 26 | Nov 30 | Dec 5 | Dec 9 | Dec 15 | Dec 23 | Jan 3 |
| 16°F | Nov 23 | Nov 30 | Dec 5 | Dec 10 | Dec 16 | Dec 24 | Dec 31 | Jan 9 | Jan 28 |
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: Lewiston Nez Perce Co Ap, Id, about 9.5 miles away@if(!empty($station['elevation_ft'])), at 1,436 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 Asotin, ID?
On average, the last spring frost (32°F) around Asotin, ID is about Apr 6. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 20.
When is the first frost in the fall?
The first fall frost around Asotin, ID typically arrives about Oct 26. 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 Apr 6 on average, or Mar 20 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 200 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 83501 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026