Last spring frost
Jun 6
Frost Dates for Inchelium, WA
First fall frost
Sep 11
Growing season
94 days
Hardiness zone
7a
In an average year around Inchelium, WA, the last spring frost (32°F) is about Jun 6 and the first fall frost is about Sep 11, giving roughly a 94-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%) |
|---|---|---|---|
| Freeze (32°F) | Jul 5 | Jun 6 | May 13 |
| Hard (28°F) | Jun 2 | May 11 | Apr 26 |
| Severe (24°F) | May 10 | Apr 25 | Apr 1 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jul 5 | Jun 24 | Jun 17 | Jun 12 | Jun 6 | Jun 1 | May 27 | May 20 | May 13 |
| 28°F | Jun 2 | May 25 | May 19 | May 14 | May 11 | May 7 | May 4 | Apr 30 | Apr 26 |
| 24°F | May 10 | May 5 | May 1 | Apr 28 | Apr 25 | Apr 22 | Apr 17 | Apr 12 | Apr 1 |
| 20°F | Apr 27 | Apr 19 | Apr 12 | Apr 3 | Mar 29 | Mar 22 | Mar 16 | Mar 10 | Mar 4 |
| 16°F | Mar 28 | Mar 17 | Mar 11 | Mar 7 | Mar 3 | Mar 1 | Feb 27 | Feb 22 | Feb 14 |
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) | Aug 26 | Sep 11 | Sep 28 |
| Hard (28°F) | Sep 9 | Sep 27 | Oct 11 |
| Severe (24°F) | Sep 27 | Oct 8 | Oct 29 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 26 | Sep 1 | Sep 4 | Sep 7 | Sep 11 | Sep 14 | Sep 18 | Sep 22 | Sep 28 |
| 28°F | Sep 9 | Sep 15 | Sep 20 | Sep 23 | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 11 |
| 24°F | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 8 | Oct 12 | Oct 16 | Oct 21 | Oct 29 |
| 20°F | Oct 5 | Oct 10 | Oct 14 | Oct 18 | Oct 22 | Oct 26 | Oct 30 | Nov 5 | Nov 13 |
| 16°F | Oct 17 | Oct 24 | Oct 28 | Nov 1 | Nov 5 | Nov 11 | Nov 16 | Nov 21 | Nov 27 |
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: Davenport, Wa, about 24.4 miles away@if(!empty($station['elevation_ft'])), at 2,369 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 Inchelium, WA?
On average, the last spring frost (32°F) around Inchelium, WA is about Jun 6. 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 Inchelium, WA typically arrives about Sep 11. 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 6 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 94 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 99129 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026