Last spring frost
May 13
Frost Dates for Roslyn, WA
First fall frost
Sep 25
Growing season
132 days
Hardiness zone
7a
In an average year around Roslyn, WA, the last spring frost (32°F) is about May 13 and the first fall frost is about Sep 25, giving roughly a 132-day growing season. To be safe most years, wait until Apr 29 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 19 | Jun 1 | May 13 |
| Freeze (32°F) | Jun 1 | May 13 | Apr 29 |
| Hard (28°F) | May 14 | Apr 28 | Apr 12 |
| Severe (24°F) | Apr 27 | Apr 4 | Mar 14 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 19 | Jun 12 | Jun 8 | Jun 4 | Jun 1 | May 29 | May 24 | May 19 | May 13 |
| 32°F | Jun 1 | May 26 | May 20 | May 16 | May 13 | May 10 | May 6 | May 2 | Apr 29 |
| 28°F | May 14 | May 8 | May 3 | May 1 | Apr 28 | Apr 24 | Apr 21 | Apr 17 | Apr 12 |
| 24°F | Apr 27 | Apr 20 | Apr 13 | Apr 9 | Apr 4 | Mar 31 | Mar 29 | Mar 23 | Mar 14 |
| 20°F | Apr 1 | Mar 25 | Mar 19 | Mar 15 | Mar 11 | Mar 8 | Mar 4 | Feb 28 | Feb 20 |
| 16°F | Mar 14 | Mar 8 | Mar 3 | Feb 28 | Feb 24 | Feb 20 | Feb 15 | Feb 7 | Jan 26 |
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 31 | Sep 11 | Sep 27 |
| Freeze (32°F) | Sep 11 | Sep 25 | Oct 7 |
| Hard (28°F) | Sep 20 | Oct 5 | Oct 23 |
| Severe (24°F) | Oct 2 | Oct 20 | Nov 7 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 31 | Sep 3 | Sep 6 | Sep 9 | Sep 11 | Sep 15 | Sep 18 | Sep 23 | Sep 27 |
| 32°F | Sep 11 | Sep 16 | Sep 19 | Sep 23 | Sep 25 | Sep 28 | Oct 1 | Oct 3 | Oct 7 |
| 28°F | Sep 20 | Sep 27 | Oct 1 | Oct 2 | Oct 5 | Oct 7 | Oct 11 | Oct 16 | Oct 23 |
| 24°F | Oct 2 | Oct 6 | Oct 11 | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Nov 1 | Nov 7 |
| 20°F | Oct 16 | Oct 24 | Oct 28 | Nov 1 | Nov 5 | Nov 11 | Nov 17 | Nov 23 | Dec 1 |
| 16°F | Oct 31 | Nov 5 | Nov 12 | Nov 20 | Nov 24 | Nov 29 | Dec 4 | Dec 9 | Dec 19 |
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: Cle Elum, Wa, about 4.8 miles away@if(!empty($station['elevation_ft'])), at 1,900 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 Roslyn, WA?
On average, the last spring frost (32°F) around Roslyn, WA is about May 13. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 29.
When is the first frost in the fall?
The first fall frost around Roslyn, WA typically arrives about Sep 25. 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 13 on average, or Apr 29 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 132 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 98941 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026