Last spring frost
May 29
Frost Dates for Marsing, ID
First fall frost
Sep 14
Growing season
108 days
Hardiness zone
7a
In an average year around Marsing, ID, the last spring frost (32°F) is about May 29 and the first fall frost is about Sep 14, giving roughly a 108-day growing season. To be safe most years, wait until May 9 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 23 | May 29 | May 9 |
| Hard (28°F) | May 25 | May 10 | Apr 25 |
| Severe (24°F) | May 13 | Apr 29 | Apr 6 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 23 | Jun 13 | Jun 7 | Jun 2 | May 29 | May 24 | May 20 | May 16 | May 9 |
| 28°F | May 25 | May 19 | May 15 | May 12 | May 10 | May 6 | May 3 | Apr 30 | Apr 25 |
| 24°F | May 13 | May 8 | May 4 | May 1 | Apr 29 | Apr 25 | Apr 20 | Apr 15 | Apr 6 |
| 20°F | May 3 | Apr 27 | Apr 20 | Apr 14 | Apr 9 | Apr 3 | Mar 29 | Mar 21 | Mar 11 |
| 16°F | Apr 18 | Apr 5 | Mar 28 | Mar 18 | Mar 11 | Mar 6 | Feb 28 | Feb 23 | Feb 13 |
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 14 | Oct 1 |
| Hard (28°F) | Sep 11 | Sep 27 | Oct 12 |
| Severe (24°F) | Sep 24 | Oct 8 | Oct 27 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Sep 1 | Sep 5 | Sep 8 | Sep 11 | Sep 14 | Sep 17 | Sep 21 | Sep 25 | Oct 1 |
| 28°F | Sep 11 | Sep 16 | Sep 20 | Sep 24 | Sep 27 | Sep 30 | Oct 3 | Oct 6 | Oct 12 |
| 24°F | Sep 24 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 16 | Oct 21 | Oct 27 |
| 20°F | Oct 5 | Oct 10 | Oct 16 | Oct 19 | Oct 23 | Oct 27 | Oct 30 | Nov 2 | Nov 8 |
| 16°F | Oct 18 | Oct 23 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 10 | Nov 16 | Nov 24 |
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: Rockville 5 N, Or, about 11.1 miles away@if(!empty($station['elevation_ft'])), at 3,670 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 Marsing, ID?
On average, the last spring frost (32°F) around Marsing, ID is about May 29. In cooler years it can run later, so for a safer bet many gardeners wait until May 9.
When is the first frost in the fall?
The first fall frost around Marsing, ID typically arrives about Sep 14. 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 29 on average, or May 9 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 108 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 83639 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026