Last spring frost
Apr 27
Frost Dates for Winthrop, WA
First fall frost
Oct 17
Growing season
173 days
Hardiness zone
6b
In an average year around Winthrop, WA, the last spring frost (32°F) is about Apr 27 and the first fall frost is about Oct 17, giving roughly a 173-day growing season. To be safe most years, wait until Apr 12 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 1 | May 10 | Apr 26 |
| Freeze (32°F) | May 12 | Apr 27 | Apr 12 |
| Hard (28°F) | Apr 24 | Apr 4 | Mar 19 |
| Severe (24°F) | Mar 31 | Mar 10 | Feb 23 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 1 | May 25 | May 19 | May 14 | May 10 | May 6 | May 3 | Apr 30 | Apr 26 |
| 32°F | May 12 | May 5 | May 2 | Apr 29 | Apr 27 | Apr 23 | Apr 20 | Apr 17 | Apr 12 |
| 28°F | Apr 24 | Apr 16 | Apr 11 | Apr 8 | Apr 4 | Apr 1 | Mar 30 | Mar 25 | Mar 19 |
| 24°F | Mar 31 | Mar 24 | Mar 19 | Mar 14 | Mar 10 | Mar 7 | Mar 3 | Feb 28 | Feb 23 |
| 20°F | Mar 11 | Mar 6 | Mar 1 | Feb 26 | Feb 21 | Feb 16 | Feb 11 | Feb 4 | Jan 22 |
| 16°F | Mar 2 | Feb 24 | Feb 18 | Feb 13 | Feb 7 | Jan 31 | Jan 22 | Jan 12 | Jan 1 |
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 23 | Oct 4 | Oct 16 |
| Freeze (32°F) | Oct 5 | Oct 17 | Oct 30 |
| Hard (28°F) | Oct 16 | Oct 31 | Nov 15 |
| Severe (24°F) | Oct 29 | Nov 17 | Dec 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 28 | Oct 1 | Oct 3 | Oct 4 | Oct 6 | Oct 9 | Oct 12 | Oct 16 |
| 32°F | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 30 |
| 28°F | Oct 16 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 10 | Nov 15 |
| 24°F | Oct 29 | Nov 4 | Nov 8 | Nov 13 | Nov 17 | Nov 21 | Nov 24 | Nov 28 | Dec 5 |
| 20°F | Nov 12 | Nov 22 | Nov 26 | Nov 30 | Dec 3 | Dec 6 | Dec 11 | Dec 17 | Dec 25 |
| 16°F | Nov 25 | Dec 2 | Dec 7 | Dec 12 | Dec 17 | Dec 22 | Dec 29 | Jan 5 | Jan 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: Stehekin 4 Nw, Wa, about 2.8 miles away@if(!empty($station['elevation_ft'])), at 1,257 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 Winthrop, WA?
On average, the last spring frost (32°F) around Winthrop, WA is about Apr 27. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 12.
When is the first frost in the fall?
The first fall frost around Winthrop, WA typically arrives about Oct 17. 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 Apr 27 on average, or Apr 12 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 173 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 98852 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026