Last spring frost
Jun 1
Frost Dates for Malta, ID
First fall frost
Sep 19
Growing season
111 days
Hardiness zone
6a
In an average year around Malta, ID, the last spring frost (32°F) is about Jun 1 and the first fall frost is about Sep 19, giving roughly a 111-day growing season. To be safe most years, wait until May 10 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) | Jul 1 | Jun 17 | Jun 1 |
| Freeze (32°F) | Jun 19 | Jun 1 | May 10 |
| Hard (28°F) | Jun 1 | May 6 | Apr 18 |
| Severe (24°F) | May 8 | Apr 19 | Mar 28 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jul 1 | Jun 26 | Jun 23 | Jun 20 | Jun 17 | Jun 14 | Jun 10 | Jun 6 | Jun 1 |
| 32°F | Jun 19 | Jun 14 | Jun 9 | Jun 5 | Jun 1 | May 28 | May 21 | May 16 | May 10 |
| 28°F | Jun 1 | May 21 | May 14 | May 10 | May 6 | May 2 | Apr 29 | Apr 25 | Apr 18 |
| 24°F | May 8 | May 2 | Apr 28 | Apr 24 | Apr 19 | Apr 14 | Apr 10 | Apr 4 | Mar 28 |
| 20°F | Apr 21 | Apr 13 | Apr 6 | Apr 2 | Mar 29 | Mar 24 | Mar 18 | Mar 12 | Mar 6 |
| 16°F | Apr 2 | Mar 26 | Mar 20 | Mar 13 | Mar 8 | Mar 5 | Mar 2 | Feb 26 | 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%) |
|---|---|---|---|
| Light (36°F) | Aug 25 | Sep 8 | Sep 27 |
| Freeze (32°F) | Sep 2 | Sep 19 | Oct 10 |
| Hard (28°F) | Sep 12 | Oct 2 | Oct 24 |
| Severe (24°F) | Sep 26 | Oct 18 | Nov 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 25 | Aug 31 | Sep 2 | Sep 5 | Sep 8 | Sep 11 | Sep 14 | Sep 19 | Sep 27 |
| 32°F | Sep 2 | Sep 7 | Sep 12 | Sep 15 | Sep 19 | Sep 23 | Sep 28 | Oct 2 | Oct 10 |
| 28°F | Sep 12 | Sep 20 | Sep 24 | Sep 28 | Oct 2 | Oct 7 | Oct 12 | Oct 18 | Oct 24 |
| 24°F | Sep 26 | Oct 2 | Oct 7 | Oct 13 | Oct 18 | Oct 23 | Oct 26 | Nov 1 | Nov 5 |
| 20°F | Oct 10 | Oct 19 | Oct 24 | Oct 28 | Nov 1 | Nov 3 | Nov 8 | Nov 13 | Nov 20 |
| 16°F | Oct 24 | Oct 30 | Nov 2 | Nov 6 | Nov 10 | Nov 15 | Nov 19 | Nov 24 | Nov 29 |
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: Malta 4 Ese, Id, about 10.6 miles away@if(!empty($station['elevation_ft'])), at 4,590 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 Malta, ID?
On average, the last spring frost (32°F) around Malta, ID is about Jun 1. In cooler years it can run later, so for a safer bet many gardeners wait until May 10.
When is the first frost in the fall?
The first fall frost around Malta, ID typically arrives about Sep 19. 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 10 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 111 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 83342 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026