Last spring frost
May 6
Frost Dates for Ferdinand, ID
First fall frost
Oct 13
Growing season
156 days
Hardiness zone
6a
In an average year around Ferdinand, ID, the last spring frost (32°F) is about May 6 and the first fall frost is about Oct 13, giving roughly a 156-day growing season. To be safe most years, wait until Apr 22 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 20 | May 31 | May 10 |
| Freeze (32°F) | May 26 | May 6 | Apr 22 |
| Hard (28°F) | May 10 | Apr 21 | Apr 1 |
| Severe (24°F) | Apr 19 | Mar 30 | Mar 8 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 20 | Jun 13 | Jun 9 | Jun 4 | May 31 | May 26 | May 22 | May 16 | May 10 |
| 32°F | May 26 | May 19 | May 15 | May 10 | May 6 | May 3 | Apr 30 | Apr 27 | Apr 22 |
| 28°F | May 10 | May 2 | Apr 29 | Apr 25 | Apr 21 | Apr 17 | Apr 13 | Apr 9 | Apr 1 |
| 24°F | Apr 19 | Apr 11 | Apr 6 | Apr 2 | Mar 30 | Mar 26 | Mar 21 | Mar 15 | Mar 8 |
| 20°F | Mar 28 | Mar 22 | Mar 16 | Mar 11 | Mar 7 | Mar 3 | Feb 28 | Feb 22 | Feb 14 |
| 16°F | Mar 12 | Mar 5 | Feb 28 | Feb 25 | Feb 21 | Feb 16 | Feb 11 | Feb 5 | Jan 24 |
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 12 | Oct 1 | Oct 14 |
| Freeze (32°F) | Sep 28 | Oct 13 | Oct 27 |
| Hard (28°F) | Oct 9 | Oct 24 | Nov 12 |
| Severe (24°F) | Oct 18 | Nov 5 | Nov 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 19 | Sep 24 | Sep 27 | Oct 1 | Oct 3 | Oct 5 | Oct 9 | Oct 14 |
| 32°F | Sep 28 | Oct 3 | Oct 6 | Oct 9 | Oct 13 | Oct 15 | Oct 18 | Oct 22 | Oct 27 |
| 28°F | Oct 9 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 28 | Oct 31 | Nov 5 | Nov 12 |
| 24°F | Oct 18 | Oct 23 | Oct 28 | Nov 1 | Nov 5 | Nov 10 | Nov 13 | Nov 17 | Nov 22 |
| 20°F | Oct 25 | Nov 2 | Nov 9 | Nov 13 | Nov 16 | Nov 20 | Nov 23 | Nov 27 | Dec 4 |
| 16°F | Nov 3 | Nov 12 | Nov 18 | Nov 23 | Nov 26 | Dec 1 | Dec 6 | Dec 10 | Dec 18 |
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: Cottonwood 2 Wsw, Id, about 7.9 miles away@if(!empty($station['elevation_ft'])), at 3,945 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 Ferdinand, ID?
On average, the last spring frost (32°F) around Ferdinand, ID is about May 6. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 22.
When is the first frost in the fall?
The first fall frost around Ferdinand, ID typically arrives about Oct 13. 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 6 on average, or Apr 22 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 156 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 83526 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026