Last spring frost
May 6
Frost Dates for Tonasket, WA
First fall frost
Oct 6
Growing season
151 days
Hardiness zone
6b
In an average year around Tonasket, WA, the last spring frost (32°F) is about May 6 and the first fall frost is about Oct 6, giving roughly a 151-day growing season. To be safe most years, wait until Apr 23 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 15 | May 25 | May 9 |
| Freeze (32°F) | May 25 | May 6 | Apr 23 |
| Hard (28°F) | May 5 | Apr 19 | Apr 4 |
| Severe (24°F) | Apr 14 | Mar 31 | Mar 15 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 15 | Jun 7 | Jun 3 | May 30 | May 25 | May 21 | May 17 | May 13 | May 9 |
| 32°F | May 25 | May 18 | May 13 | May 9 | May 6 | May 3 | Apr 30 | Apr 27 | Apr 23 |
| 28°F | May 5 | Apr 30 | Apr 26 | Apr 22 | Apr 19 | Apr 16 | Apr 12 | Apr 9 | Apr 4 |
| 24°F | Apr 14 | Apr 9 | Apr 5 | Apr 3 | Mar 31 | Mar 29 | Mar 25 | Mar 22 | Mar 15 |
| 20°F | Mar 30 | Mar 25 | Mar 20 | Mar 17 | Mar 14 | Mar 11 | Mar 8 | Mar 5 | Mar 1 |
| 16°F | Mar 17 | Mar 12 | Mar 8 | Mar 6 | Mar 4 | Mar 1 | Feb 27 | Feb 21 | Feb 16 |
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 12 | Sep 25 | Oct 6 |
| Freeze (32°F) | Sep 24 | Oct 6 | Oct 18 |
| Hard (28°F) | Oct 4 | Oct 18 | Oct 31 |
| Severe (24°F) | Oct 14 | Oct 28 | Nov 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 17 | Sep 20 | Sep 23 | Sep 25 | Sep 28 | Sep 30 | Oct 3 | Oct 6 |
| 32°F | Sep 24 | Sep 28 | Oct 1 | Oct 3 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 18 |
| 28°F | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 31 |
| 24°F | Oct 14 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 30 | Nov 2 | Nov 6 | Nov 11 |
| 20°F | Oct 23 | Oct 29 | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 20 | Nov 24 |
| 16°F | Nov 1 | Nov 8 | Nov 12 | Nov 16 | Nov 21 | Nov 23 | Nov 26 | Nov 30 | Dec 6 |
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: Tonasket 11Ne, Wa, about 8.5 miles away@if(!empty($station['elevation_ft'])), at 3,434 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 Tonasket, WA?
On average, the last spring frost (32°F) around Tonasket, WA is about May 6. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 23.
When is the first frost in the fall?
The first fall frost around Tonasket, WA typically arrives about Oct 6. 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 6 on average, or Apr 23 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 151 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 98855 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026