Last spring frost
Jun 1
Frost Dates for Garden Valley, ID
First fall frost
Sep 10
Growing season
102 days
Hardiness zone
6b
In an average year around Garden Valley, ID, the last spring frost (32°F) is about Jun 1 and the first fall frost is about Sep 10, giving roughly a 102-day growing season. To be safe most years, wait until May 13 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 20 | Jun 1 | May 13 |
| Hard (28°F) | May 30 | May 11 | Apr 26 |
| Severe (24°F) | May 11 | Apr 22 | Mar 29 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 20 | Jun 14 | Jun 10 | Jun 6 | Jun 1 | May 27 | May 23 | May 18 | May 13 |
| 28°F | May 30 | May 22 | May 17 | May 14 | May 11 | May 7 | May 4 | May 1 | Apr 26 |
| 24°F | May 11 | May 4 | Apr 30 | Apr 26 | Apr 22 | Apr 17 | Apr 11 | Apr 4 | Mar 29 |
| 20°F | Apr 18 | Apr 9 | Apr 1 | Mar 29 | Mar 22 | Mar 17 | Mar 13 | Mar 9 | Mar 4 |
| 16°F | Mar 19 | Mar 14 | Mar 10 | Mar 6 | Mar 4 | Mar 2 | Feb 28 | Feb 24 | Feb 18 |
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) | Aug 28 | Sep 10 | Sep 27 |
| Hard (28°F) | Sep 8 | Sep 24 | Oct 10 |
| Severe (24°F) | Sep 22 | Oct 8 | Oct 29 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 28 | Sep 1 | Sep 4 | Sep 6 | Sep 10 | Sep 13 | Sep 17 | Sep 20 | Sep 27 |
| 28°F | Sep 8 | Sep 14 | Sep 18 | Sep 21 | Sep 24 | Sep 28 | Oct 1 | Oct 4 | Oct 10 |
| 24°F | Sep 22 | Sep 28 | Oct 1 | Oct 4 | Oct 8 | Oct 12 | Oct 17 | Oct 22 | Oct 29 |
| 20°F | Oct 4 | Oct 10 | Oct 16 | Oct 21 | Oct 26 | Oct 31 | Nov 3 | Nov 8 | Nov 18 |
| 16°F | Oct 20 | Oct 27 | Nov 1 | Nov 5 | Nov 10 | Nov 15 | Nov 21 | Nov 26 | Dec 2 |
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: Garden Valley, Id, about 4.2 miles away@if(!empty($station['elevation_ft'])), at 3,100 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 Garden Valley, ID?
On average, the last spring frost (32°F) around Garden Valley, ID is about Jun 1. In cooler years it can run later, so for a safer bet many gardeners wait until May 13.
When is the first frost in the fall?
The first fall frost around Garden Valley, ID typically arrives about Sep 10. 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 Jun 1 on average, or May 13 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 102 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 83622 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026