Last spring frost
May 30
Frost Dates for Curlew, WA
First fall frost
Sep 10
Growing season
102 days
Hardiness zone
6a
In an average year around Curlew, WA, the last spring frost (32°F) is about May 30 and the first fall frost is about Sep 10, giving roughly a 102-day growing season. To be safe most years, wait until May 11 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 17 | May 30 | May 11 |
| Hard (28°F) | May 28 | May 12 | Apr 27 |
| Severe (24°F) | May 12 | Apr 27 | Apr 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Jun 17 | Jun 11 | Jun 5 | Jun 1 | May 30 | May 27 | May 23 | May 17 | May 11 |
| 28°F | May 28 | May 22 | May 17 | May 14 | May 12 | May 8 | May 5 | Apr 30 | Apr 27 |
| 24°F | May 12 | May 7 | May 3 | Apr 30 | Apr 27 | Apr 24 | Apr 20 | Apr 17 | Apr 11 |
| 20°F | Apr 28 | Apr 21 | Apr 15 | Apr 9 | Apr 6 | Apr 3 | Mar 31 | Mar 27 | Mar 19 |
| 16°F | Apr 4 | Mar 30 | Mar 26 | Mar 20 | Mar 17 | Mar 14 | Mar 11 | Mar 7 | Mar 3 |
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 10 | Sep 25 |
| Hard (28°F) | Sep 11 | Sep 24 | Oct 5 |
| Severe (24°F) | Sep 23 | Oct 5 | Oct 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 32°F | Aug 28 | Sep 2 | Sep 5 | Sep 7 | Sep 10 | Sep 13 | Sep 16 | Sep 20 | Sep 25 |
| 28°F | Sep 11 | Sep 15 | Sep 18 | Sep 21 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 5 |
| 24°F | Sep 23 | Sep 28 | Oct 1 | Oct 2 | Oct 5 | Oct 7 | Oct 11 | Oct 14 | Oct 19 |
| 20°F | Oct 1 | Oct 6 | Oct 10 | Oct 14 | Oct 18 | Oct 22 | Oct 25 | Oct 30 | Nov 5 |
| 16°F | Oct 12 | Oct 19 | Oct 24 | Oct 29 | Oct 31 | Nov 3 | Nov 7 | Nov 13 | Nov 20 |
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: Republic, Wa, about 17.9 miles away@if(!empty($station['elevation_ft'])), at 2,555 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 Curlew, WA?
On average, the last spring frost (32°F) around Curlew, WA is about May 30. In cooler years it can run later, so for a safer bet many gardeners wait until May 11.
When is the first frost in the fall?
The first fall frost around Curlew, WA typically arrives about Sep 10. 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 30 on average, or May 11 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 102 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 99118 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026