Last spring frost
Apr 5
Frost Dates for Onalaska, WA
First fall frost
Oct 25
Growing season
196 days
Hardiness zone
8a
In an average year around Onalaska, WA, the last spring frost (32°F) is about Apr 5 and the first fall frost is about Oct 25, giving roughly a 196-day growing season. To be safe most years, wait until Mar 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) | May 30 | May 2 | Apr 6 |
| Freeze (32°F) | May 4 | Apr 5 | Mar 12 |
| Hard (28°F) | Apr 8 | Mar 10 | Feb 15 |
| Severe (24°F) | Mar 13 | Feb 21 | Dec 21 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 30 | May 19 | May 13 | May 7 | May 2 | Apr 29 | Apr 25 | Apr 17 | Apr 6 |
| 32°F | May 4 | Apr 27 | Apr 20 | Apr 13 | Apr 5 | Mar 31 | Mar 27 | Mar 21 | Mar 12 |
| 28°F | Apr 8 | Mar 31 | Mar 23 | Mar 16 | Mar 10 | Mar 5 | Feb 28 | Feb 24 | Feb 15 |
| 24°F | Mar 13 | Mar 5 | Feb 28 | Feb 25 | Feb 21 | Feb 16 | Feb 8 | Jan 18 | Dec 21 |
| 20°F | Feb 28 | Feb 22 | Feb 17 | Feb 12 | Feb 1 | Jan 10 | Dec 26 | Dec 11 | Nov 25 |
| 16°F | Feb 19 | Feb 14 | Feb 2 | Jan 18 | Jan 3 | Dec 27 | Dec 14 | Dec 4 | Nov 22 |
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 8 | Oct 2 | Oct 31 |
| Freeze (32°F) | Sep 24 | Oct 25 | Nov 20 |
| Hard (28°F) | Oct 6 | Nov 9 | Dec 14 |
| Severe (24°F) | Oct 22 | Nov 26 | Jan 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 8 | Sep 15 | Sep 22 | Sep 28 | Oct 2 | Oct 6 | Oct 12 | Oct 19 | Oct 31 |
| 32°F | Sep 24 | Oct 2 | Oct 11 | Oct 19 | Oct 25 | Oct 31 | Nov 4 | Nov 11 | Nov 20 |
| 28°F | Oct 6 | Oct 20 | Oct 29 | Nov 3 | Nov 9 | Nov 16 | Nov 22 | Nov 30 | Dec 14 |
| 24°F | Oct 22 | Nov 2 | Nov 11 | Nov 21 | Nov 26 | Dec 3 | Dec 13 | Dec 28 | Jan 19 |
| 20°F | Nov 4 | Nov 17 | Nov 27 | Dec 4 | Dec 13 | Dec 25 | Jan 4 | Jan 30 | Feb 16 |
| 16°F | Nov 12 | Nov 26 | Dec 7 | Dec 15 | Dec 27 | Jan 3 | Jan 23 | Feb 10 | Feb 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: Toledo Faa Ap, Wa, about 5.5 miles away@if(!empty($station['elevation_ft'])), at 379 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 Onalaska, WA?
On average, the last spring frost (32°F) around Onalaska, WA is about Apr 5. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 12.
When is the first frost in the fall?
The first fall frost around Onalaska, WA typically arrives about Oct 25. 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 5 on average, or Mar 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 196 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 98542 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026