Last spring frost
May 22
Frost Dates for Manson, WA
First fall frost
Sep 22
Growing season
121 days
Hardiness zone
7a
In an average year around Manson, WA, the last spring frost (32°F) is about May 22 and the first fall frost is about Sep 22, giving roughly a 121-day growing season. To be safe most years, wait until May 2 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 13 | May 24 |
| Freeze (32°F) | Jun 13 | May 22 | May 2 |
| Hard (28°F) | May 20 | May 3 | Apr 19 |
| Severe (24°F) | May 3 | Apr 13 | Mar 21 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jul 1 | Jun 26 | Jun 21 | Jun 17 | Jun 13 | Jun 8 | Jun 4 | May 30 | May 24 |
| 32°F | Jun 13 | Jun 5 | May 31 | May 26 | May 22 | May 18 | May 14 | May 9 | May 2 |
| 28°F | May 20 | May 14 | May 9 | May 6 | May 3 | Apr 30 | Apr 27 | Apr 24 | Apr 19 |
| 24°F | May 3 | Apr 26 | Apr 22 | Apr 17 | Apr 13 | Apr 6 | Apr 2 | Mar 29 | Mar 21 |
| 20°F | Apr 7 | Mar 31 | Mar 24 | Mar 20 | Mar 16 | Mar 12 | Mar 9 | Mar 6 | Mar 1 |
| 16°F | Mar 16 | Mar 11 | Mar 7 | Mar 4 | Mar 1 | Feb 27 | Feb 22 | Feb 17 | Feb 11 |
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 24 | Sep 8 | Sep 21 |
| Freeze (32°F) | Sep 7 | Sep 22 | Oct 4 |
| Hard (28°F) | Sep 22 | Oct 4 | Oct 20 |
| Severe (24°F) | Oct 4 | Oct 23 | Nov 9 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 24 | Aug 30 | Sep 2 | Sep 5 | Sep 8 | Sep 10 | Sep 13 | Sep 17 | Sep 21 |
| 32°F | Sep 7 | Sep 12 | Sep 16 | Sep 19 | Sep 22 | Sep 25 | Sep 27 | Sep 30 | Oct 4 |
| 28°F | Sep 22 | Sep 27 | Oct 1 | Oct 2 | Oct 4 | Oct 8 | Oct 11 | Oct 15 | Oct 20 |
| 24°F | Oct 4 | Oct 10 | Oct 15 | Oct 19 | Oct 23 | Oct 26 | Oct 30 | Nov 2 | Nov 9 |
| 20°F | Oct 19 | Oct 27 | Oct 31 | Nov 4 | Nov 8 | Nov 13 | Nov 18 | Nov 22 | Nov 29 |
| 16°F | Oct 31 | Nov 7 | Nov 13 | Nov 19 | Nov 24 | Nov 28 | Dec 3 | Dec 7 | Dec 16 |
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: Plain, Wa, about 13.4 miles away@if(!empty($station['elevation_ft'])), at 1,936 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 Manson, WA?
On average, the last spring frost (32°F) around Manson, WA is about May 22. In cooler years it can run later, so for a safer bet many gardeners wait until May 2.
When is the first frost in the fall?
The first fall frost around Manson, WA typically arrives about Sep 22. 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 22 on average, or May 2 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 121 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 98822 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026