Last spring frost
May 22
Frost Dates for Loon Lake, WA
First fall frost
Sep 14
Growing season
112 days
Hardiness zone
6a
In an average year around Loon Lake, WA, the last spring frost (32°F) is about May 22 and the first fall frost is about Sep 14, giving roughly a 112-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%) |
|---|---|---|---|
| Freeze (32°F) | Jun 15 | May 22 | May 2 |
| Hard (28°F) | May 21 | May 3 | Apr 18 |
| Severe (24°F) | May 7 | Apr 19 | Mar 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 15 | Jun 5 | May 31 | May 27 | May 22 | May 17 | May 13 | May 8 | May 2 |
| 28°F | May 21 | May 14 | May 11 | May 6 | May 3 | Apr 30 | Apr 28 | Apr 23 | Apr 18 |
| 24°F | May 7 | May 1 | Apr 27 | Apr 22 | Apr 19 | Apr 14 | Apr 7 | Mar 31 | Mar 24 |
| 20°F | Apr 20 | Apr 9 | Apr 3 | Mar 29 | Mar 24 | Mar 19 | Mar 14 | Mar 10 | Mar 5 |
| 16°F | Mar 24 | Mar 16 | Mar 12 | Mar 8 | Mar 6 | Mar 3 | Feb 28 | Feb 24 | 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%) |
|---|---|---|---|
| Freeze (32°F) | Aug 28 | Sep 14 | Oct 1 |
| Hard (28°F) | Sep 14 | Sep 29 | Oct 14 |
| Severe (24°F) | Sep 27 | Oct 10 | Nov 3 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 28 | Sep 3 | Sep 7 | Sep 10 | Sep 14 | Sep 18 | Sep 21 | Sep 25 | Oct 1 |
| 28°F | Sep 14 | Sep 19 | Sep 23 | Sep 27 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 14 |
| 24°F | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 10 | Oct 15 | Oct 20 | Oct 25 | Nov 3 |
| 20°F | Oct 5 | Oct 12 | Oct 17 | Oct 23 | Oct 27 | Oct 31 | Nov 5 | Nov 11 | Nov 20 |
| 16°F | Oct 18 | Oct 26 | Oct 31 | Nov 4 | Nov 10 | Nov 14 | Nov 20 | Nov 25 | Dec 2 |
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: Deer Park Ap, Wa, about 11.3 miles away@if(!empty($station['elevation_ft'])), at 2,191 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 Loon Lake, WA?
On average, the last spring frost (32°F) around Loon Lake, 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 Loon Lake, WA typically arrives about Sep 14. 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 112 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 99148 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026