Last spring frost
Apr 28
Frost Dates for Thorp, WA
First fall frost
Oct 7
Growing season
163 days
Hardiness zone
7a
In an average year around Thorp, WA, the last spring frost (32°F) is about Apr 28 and the first fall frost is about Oct 7, giving roughly a 163-day growing season. To be safe most years, wait until Apr 13 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 5 | May 11 | Apr 28 |
| Freeze (32°F) | May 12 | Apr 28 | Apr 13 |
| Hard (28°F) | Apr 30 | Apr 11 | Mar 24 |
| Severe (24°F) | Apr 13 | Mar 23 | Mar 2 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 5 | May 26 | May 18 | May 14 | May 11 | May 7 | May 4 | May 1 | Apr 28 |
| 32°F | May 12 | May 7 | May 3 | Apr 30 | Apr 28 | Apr 25 | Apr 22 | Apr 18 | Apr 13 |
| 28°F | Apr 30 | Apr 24 | Apr 19 | Apr 15 | Apr 11 | Apr 8 | Apr 4 | Mar 31 | Mar 24 |
| 24°F | Apr 13 | Apr 6 | Apr 1 | Mar 27 | Mar 23 | Mar 18 | Mar 14 | Mar 10 | Mar 2 |
| 20°F | Mar 24 | Mar 15 | Mar 10 | Mar 5 | Mar 1 | Feb 26 | Feb 22 | Feb 15 | Feb 5 |
| 16°F | Mar 7 | Mar 1 | Feb 25 | Feb 19 | Feb 13 | Feb 6 | Jan 31 | Jan 22 | Jan 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) | Sep 12 | Sep 26 | Oct 7 |
| Freeze (32°F) | Sep 26 | Oct 7 | Oct 22 |
| Hard (28°F) | Oct 7 | Oct 20 | Nov 3 |
| Severe (24°F) | Oct 17 | Nov 1 | Nov 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 12 | Sep 17 | Sep 21 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 3 | Oct 7 |
| 32°F | Sep 26 | Oct 1 | Oct 3 | Oct 5 | Oct 7 | Oct 10 | Oct 14 | Oct 17 | Oct 22 |
| 28°F | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 30 | Nov 3 |
| 24°F | Oct 17 | Oct 22 | Oct 25 | Oct 29 | Nov 1 | Nov 4 | Nov 7 | Nov 12 | Nov 18 |
| 20°F | Oct 27 | Nov 1 | Nov 6 | Nov 11 | Nov 15 | Nov 19 | Nov 24 | Nov 28 | Dec 4 |
| 16°F | Nov 5 | Nov 12 | Nov 19 | Nov 25 | Nov 29 | Dec 3 | Dec 8 | Dec 17 | Dec 30 |
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: Ellensburg Bowers Fld, Wa, about 10.9 miles away@if(!empty($station['elevation_ft'])), at 1,766 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 Thorp, WA?
On average, the last spring frost (32°F) around Thorp, WA is about Apr 28. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 13.
When is the first frost in the fall?
The first fall frost around Thorp, WA typically arrives about Oct 7. 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 28 on average, or Apr 13 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 163 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 98946 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026