Last spring frost
Apr 6
Frost Dates for Chinook, WA
First fall frost
Oct 26
Growing season
200 days
Hardiness zone
8b
In an average year around Chinook, WA, the last spring frost (32°F) is about Apr 6 and the first fall frost is about Oct 26, giving roughly a 200-day growing season. To be safe most years, wait until Mar 16 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) | May 18 | Apr 30 | Apr 15 |
| Freeze (32°F) | Apr 28 | Apr 6 | Mar 16 |
| Hard (28°F) | Mar 30 | Mar 6 | Feb 9 |
| Severe (24°F) | Mar 1 | Feb 8 | Dec 16 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 18 | May 11 | May 7 | May 3 | Apr 30 | Apr 28 | Apr 25 | Apr 21 | Apr 15 |
| 32°F | Apr 28 | Apr 20 | Apr 16 | Apr 11 | Apr 6 | Apr 1 | Mar 28 | Mar 24 | Mar 16 |
| 28°F | Mar 30 | Mar 22 | Mar 16 | Mar 12 | Mar 6 | Feb 28 | Feb 26 | Feb 20 | Feb 9 |
| 24°F | Mar 1 | Feb 26 | Feb 21 | Feb 15 | Feb 8 | Jan 31 | Jan 21 | Jan 5 | Dec 16 |
| 20°F | Feb 18 | Feb 9 | Jan 31 | Jan 20 | Jan 8 | Dec 31 | Dec 20 | Dec 10 | Dec 2 |
| 16°F | Feb 12 | Jan 31 | Jan 13 | Jan 1 | Dec 23 | Dec 17 | Dec 10 | Dec 4 | Nov 29 |
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 22 | Oct 6 | Oct 27 |
| Freeze (32°F) | Oct 4 | Oct 26 | Nov 16 |
| Hard (28°F) | Oct 22 | Nov 13 | Dec 15 |
| Severe (24°F) | Nov 3 | Dec 5 | Jan 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 22 | Sep 28 | Oct 1 | Oct 4 | Oct 6 | Oct 10 | Oct 15 | Oct 20 | Oct 27 |
| 32°F | Oct 4 | Oct 13 | Oct 18 | Oct 22 | Oct 26 | Oct 30 | Nov 2 | Nov 8 | Nov 16 |
| 28°F | Oct 22 | Oct 30 | Nov 3 | Nov 8 | Nov 13 | Nov 18 | Nov 25 | Dec 2 | Dec 15 |
| 24°F | Nov 3 | Nov 14 | Nov 23 | Nov 30 | Dec 5 | Dec 13 | Dec 23 | Jan 2 | Jan 24 |
| 20°F | Nov 18 | Nov 30 | Dec 5 | Dec 13 | Dec 20 | Dec 31 | Jan 7 | Jan 24 | Feb 9 |
| 16°F | Nov 28 | Dec 1 | Dec 8 | Dec 13 | Dec 20 | Dec 27 | Jan 5 | Jan 22 | Feb 9 |
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: Long Beach Exp Stn, Wa, about 8.1 miles away@if(!empty($station['elevation_ft'])), at 25 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 Chinook, WA?
On average, the last spring frost (32°F) around Chinook, WA is about Apr 6. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 16.
When is the first frost in the fall?
The first fall frost around Chinook, WA typically arrives about Oct 26. 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 6 on average, or Mar 16 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 200 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 98614 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026