Last spring frost
May 21
Frost Dates for Melba, ID
First fall frost
Sep 28
Growing season
126 days
Hardiness zone
7a
In an average year around Melba, ID, the last spring frost (32°F) is about May 21 and the first fall frost is about Sep 28, giving roughly a 126-day growing season. To be safe most years, wait until May 4 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 26 | Jun 10 | May 23 |
| Freeze (32°F) | Jun 12 | May 21 | May 4 |
| Hard (28°F) | May 22 | May 5 | Apr 21 |
| Severe (24°F) | May 8 | Apr 20 | Apr 1 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 26 | Jun 21 | Jun 17 | Jun 14 | Jun 10 | Jun 7 | Jun 3 | May 31 | May 23 |
| 32°F | Jun 12 | Jun 6 | Jun 1 | May 25 | May 21 | May 17 | May 14 | May 10 | May 4 |
| 28°F | May 22 | May 16 | May 13 | May 9 | May 5 | May 2 | Apr 28 | Apr 25 | Apr 21 |
| 24°F | May 8 | May 2 | Apr 27 | Apr 24 | Apr 20 | Apr 15 | Apr 10 | Apr 6 | Apr 1 |
| 20°F | Apr 20 | Apr 11 | Apr 6 | Apr 2 | Mar 29 | Mar 24 | Mar 19 | Mar 13 | Mar 5 |
| 16°F | Apr 1 | Mar 23 | Mar 14 | Mar 9 | Mar 4 | Feb 28 | Feb 23 | Feb 17 | Feb 8 |
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 15 | Sep 30 |
| Freeze (32°F) | Sep 13 | Sep 28 | Oct 10 |
| Hard (28°F) | Sep 24 | Oct 8 | Oct 23 |
| Severe (24°F) | Oct 5 | Oct 22 | Nov 6 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 1 | Sep 5 | Sep 9 | Sep 12 | Sep 15 | Sep 18 | Sep 21 | Sep 25 | Sep 30 |
| 32°F | Sep 13 | Sep 18 | Sep 22 | Sep 25 | Sep 28 | Sep 30 | Oct 3 | Oct 6 | Oct 10 |
| 28°F | Sep 24 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 18 | Oct 23 |
| 24°F | Oct 5 | Oct 10 | Oct 15 | Oct 18 | Oct 22 | Oct 25 | Oct 28 | Nov 1 | Nov 6 |
| 20°F | Oct 17 | Oct 22 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 9 | Nov 14 | Nov 20 |
| 16°F | Oct 24 | Oct 31 | Nov 4 | Nov 8 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Dec 1 |
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: Reynolds, Id, about 11.5 miles away@if(!empty($station['elevation_ft'])), at 3,930 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 Melba, ID?
On average, the last spring frost (32°F) around Melba, ID is about May 21. In cooler years it can run later, so for a safer bet many gardeners wait until May 4.
When is the first frost in the fall?
The first fall frost around Melba, 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 21 on average, or May 4 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 126 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 83641 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026