Last spring frost
Mar 26
Frost Dates for Fern Prairie, WA
First fall frost
Nov 17
Growing season
237 days
Hardiness zone
8b
In an average year around Fern Prairie, WA, the last spring frost (32°F) is about Mar 26 and the first fall frost is about Nov 17, giving roughly a 237-day growing season. To be safe most years, wait until Feb 27 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 9 | Apr 24 | Apr 3 |
| Freeze (32°F) | Apr 21 | Mar 26 | Feb 27 |
| Hard (28°F) | Mar 21 | Feb 22 | Jan 15 |
| Severe (24°F) | Feb 23 | Jan 28 | Dec 18 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 9 | May 3 | Apr 30 | Apr 27 | Apr 24 | Apr 20 | Apr 17 | Apr 11 | Apr 3 |
| 32°F | Apr 21 | Apr 12 | Apr 5 | Mar 31 | Mar 26 | Mar 21 | Mar 14 | Mar 5 | Feb 27 |
| 28°F | Mar 21 | Mar 10 | Mar 3 | Feb 27 | Feb 22 | Feb 17 | Feb 10 | Jan 31 | Jan 15 |
| 24°F | Feb 23 | Feb 16 | Feb 11 | Feb 2 | Jan 28 | Jan 19 | Jan 11 | Jan 2 | Dec 18 |
| 20°F | Feb 20 | Feb 11 | Feb 1 | Jan 26 | Jan 19 | Jan 13 | Jan 7 | Dec 30 | Dec 14 |
| 16°F | Feb 4 | Jan 30 | Jan 24 | Jan 18 | Jan 14 | Jan 11 | Jan 6 | Jan 1 | Dec 24 |
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) | Oct 11 | Oct 30 | Nov 21 |
| Freeze (32°F) | Oct 26 | Nov 17 | Dec 10 |
| Hard (28°F) | Nov 14 | Dec 7 | Jan 11 |
| Severe (24°F) | Nov 28 | Dec 28 | Feb 6 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 11 | Oct 17 | Oct 22 | Oct 25 | Oct 30 | Nov 3 | Nov 9 | Nov 13 | Nov 21 |
| 32°F | Oct 26 | Nov 1 | Nov 8 | Nov 13 | Nov 17 | Nov 22 | Nov 28 | Dec 3 | Dec 10 |
| 28°F | Nov 14 | Nov 21 | Nov 28 | Dec 2 | Dec 7 | Dec 12 | Dec 21 | Dec 30 | Jan 11 |
| 24°F | Nov 28 | Dec 5 | Dec 10 | Dec 18 | Dec 28 | Jan 3 | Jan 10 | Jan 22 | Feb 6 |
| 20°F | Dec 5 | Dec 16 | Dec 25 | Jan 1 | Jan 6 | Jan 14 | Jan 20 | Feb 1 | Feb 14 |
| 16°F | Dec 14 | Dec 26 | Jan 3 | Jan 7 | Jan 12 | Jan 16 | Jan 19 | Jan 27 | Feb 1 |
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: Troutdale, Or, about 6.2 miles away@if(!empty($station['elevation_ft'])), at 33 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 Fern Prairie, WA?
On average, the last spring frost (32°F) around Fern Prairie, WA is about Mar 26. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 27.
When is the first frost in the fall?
The first fall frost around Fern Prairie, WA typically arrives about Nov 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 Mar 26 on average, or Feb 27 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 237 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 98607 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026