Last spring frost
May 8
Frost Dates for Ponderay, ID
First fall frost
Sep 28
Growing season
141 days
Hardiness zone
6b
In an average year around Ponderay, ID, the last spring frost (32°F) is about May 8 and the first fall frost is about Sep 28, giving roughly a 141-day growing season. To be safe most years, wait until Apr 23 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) | Jun 17 | May 28 | May 11 |
| Freeze (32°F) | May 25 | May 8 | Apr 23 |
| Hard (28°F) | May 7 | Apr 21 | Mar 31 |
| Severe (24°F) | Apr 20 | Mar 29 | Mar 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 17 | Jun 10 | Jun 4 | May 31 | May 28 | May 25 | May 21 | May 17 | May 11 |
| 32°F | May 25 | May 20 | May 15 | May 12 | May 8 | May 4 | May 1 | Apr 28 | Apr 23 |
| 28°F | May 7 | May 1 | Apr 28 | Apr 24 | Apr 21 | Apr 16 | Apr 12 | Apr 6 | Mar 31 |
| 24°F | Apr 20 | Apr 11 | Apr 6 | Mar 31 | Mar 29 | Mar 25 | Mar 22 | Mar 17 | Mar 11 |
| 20°F | Mar 30 | Mar 23 | Mar 19 | Mar 14 | Mar 11 | Mar 8 | Mar 4 | Mar 1 | Feb 23 |
| 16°F | Mar 17 | Mar 11 | Mar 7 | Mar 4 | Mar 1 | Feb 27 | Feb 21 | Feb 15 | Feb 4 |
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) | Sep 1 | Sep 13 | Sep 27 |
| Freeze (32°F) | Sep 11 | Sep 28 | Oct 11 |
| Hard (28°F) | Sep 25 | Oct 10 | Oct 29 |
| Severe (24°F) | Oct 5 | Oct 25 | Nov 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 1 | Sep 4 | Sep 7 | Sep 10 | Sep 13 | Sep 16 | Sep 20 | Sep 23 | Sep 27 |
| 32°F | Sep 11 | Sep 18 | Sep 22 | Sep 25 | Sep 28 | Sep 30 | Oct 2 | Oct 5 | Oct 11 |
| 28°F | Sep 25 | Oct 1 | Oct 4 | Oct 6 | Oct 10 | Oct 13 | Oct 17 | Oct 22 | Oct 29 |
| 24°F | Oct 5 | Oct 12 | Oct 17 | Oct 21 | Oct 25 | Oct 30 | Nov 2 | Nov 9 | Nov 16 |
| 20°F | Oct 20 | Oct 26 | Nov 1 | Nov 5 | Nov 10 | Nov 15 | Nov 21 | Nov 26 | Dec 4 |
| 16°F | Oct 31 | Nov 8 | Nov 14 | Nov 22 | Nov 27 | Dec 1 | Dec 5 | Dec 10 | Dec 19 |
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: Sandpoint Exp Stn, Id, about 2.1 miles away@if(!empty($station['elevation_ft'])), at 2,126 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 Ponderay, ID?
On average, the last spring frost (32°F) around Ponderay, ID is about May 8. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 23.
When is the first frost in the fall?
The first fall frost around Ponderay, ID typically arrives about Sep 28. 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 8 on average, or Apr 23 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 141 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 83852 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026