Last spring frost
May 31
Frost Dates for Oxford, ID
First fall frost
Sep 18
Growing season
110 days
Hardiness zone
5b
In an average year around Oxford, ID, the last spring frost (32°F) is about May 31 and the first fall frost is about Sep 18, giving roughly a 110-day growing season. To be safe most years, wait until May 13 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 30 | Jun 17 | Jun 3 |
| Freeze (32°F) | Jun 16 | May 31 | May 13 |
| Hard (28°F) | May 31 | May 9 | Apr 23 |
| Severe (24°F) | May 8 | Apr 22 | Apr 6 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 30 | Jun 26 | Jun 23 | Jun 20 | Jun 17 | Jun 15 | Jun 12 | Jun 9 | Jun 3 |
| 32°F | Jun 16 | Jun 12 | Jun 7 | Jun 3 | May 31 | May 28 | May 23 | May 18 | May 13 |
| 28°F | May 31 | May 23 | May 16 | May 13 | May 9 | May 6 | May 3 | Apr 30 | Apr 23 |
| 24°F | May 8 | May 3 | Apr 30 | Apr 26 | Apr 22 | Apr 19 | Apr 15 | Apr 12 | Apr 6 |
| 20°F | Apr 22 | Apr 16 | Apr 10 | Apr 7 | Apr 3 | Mar 31 | Mar 28 | Mar 22 | Mar 14 |
| 16°F | Apr 6 | Mar 31 | Mar 27 | Mar 22 | Mar 17 | Mar 13 | Mar 9 | Mar 6 | Feb 28 |
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 23 | Sep 7 | Sep 21 |
| Freeze (32°F) | Sep 3 | Sep 18 | Oct 5 |
| Hard (28°F) | Sep 15 | Oct 1 | Oct 17 |
| Severe (24°F) | Sep 28 | Oct 15 | Nov 1 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 23 | Aug 29 | Sep 1 | Sep 4 | Sep 7 | Sep 10 | Sep 12 | Sep 16 | Sep 21 |
| 32°F | Sep 3 | Sep 9 | Sep 12 | Sep 15 | Sep 18 | Sep 21 | Sep 26 | Sep 30 | Oct 5 |
| 28°F | Sep 15 | Sep 20 | Sep 25 | Sep 28 | Oct 1 | Oct 4 | Oct 7 | Oct 12 | Oct 17 |
| 24°F | Sep 28 | Oct 3 | Oct 6 | Oct 10 | Oct 15 | Oct 18 | Oct 22 | Oct 25 | Nov 1 |
| 20°F | Oct 10 | Oct 17 | Oct 22 | Oct 25 | Oct 27 | Nov 1 | Nov 4 | Nov 8 | Nov 14 |
| 16°F | Oct 24 | Oct 29 | Nov 1 | Nov 5 | Nov 9 | Nov 13 | Nov 17 | Nov 21 | Nov 26 |
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: Downey, Id, about 11.7 miles away@if(!empty($station['elevation_ft'])), at 4,865 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 Oxford, ID?
On average, the last spring frost (32°F) around Oxford, ID is about May 31. In cooler years it can run later, so for a safer bet many gardeners wait until May 13.
When is the first frost in the fall?
The first fall frost around Oxford, ID typically arrives about Sep 18. 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 31 on average, or May 13 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 110 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 83281 Planting calendar → Idaho frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026