Last spring frost
Apr 17
Frost Dates for Cathcart, WA
First fall frost
Oct 23
Growing season
188 days
Hardiness zone
8b
In an average year around Cathcart, WA, the last spring frost (32°F) is about Apr 17 and the first fall frost is about Oct 23, giving roughly a 188-day growing season. To be safe most years, wait until Mar 29 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 20 | May 5 | Apr 20 |
| Freeze (32°F) | May 7 | Apr 17 | Mar 29 |
| Hard (28°F) | Apr 14 | Mar 26 | Mar 6 |
| Severe (24°F) | Mar 22 | Feb 28 | Jan 31 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 20 | May 15 | May 11 | May 8 | May 5 | May 2 | Apr 29 | Apr 26 | Apr 20 |
| 32°F | May 7 | May 1 | Apr 27 | Apr 22 | Apr 17 | Apr 12 | Apr 8 | Apr 3 | Mar 29 |
| 28°F | Apr 14 | Apr 7 | Apr 2 | Mar 29 | Mar 26 | Mar 22 | Mar 17 | Mar 13 | Mar 6 |
| 24°F | Mar 22 | Mar 15 | Mar 10 | Mar 4 | Feb 28 | Feb 25 | Feb 19 | Feb 13 | Jan 31 |
| 20°F | Feb 28 | Feb 24 | Feb 18 | Feb 11 | Feb 2 | Jan 23 | Jan 8 | Dec 30 | Dec 10 |
| 16°F | Feb 18 | Feb 6 | Jan 27 | Jan 14 | Jan 4 | Dec 25 | Dec 13 | Dec 8 | Nov 30 |
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 21 | Oct 6 | Oct 25 |
| Freeze (32°F) | Oct 7 | Oct 23 | Nov 9 |
| Hard (28°F) | Oct 20 | Nov 8 | Nov 26 |
| Severe (24°F) | Nov 1 | Nov 23 | Dec 22 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 21 | Sep 27 | Oct 1 | Oct 3 | Oct 6 | Oct 10 | Oct 14 | Oct 18 | Oct 25 |
| 32°F | Oct 7 | Oct 13 | Oct 16 | Oct 20 | Oct 23 | Oct 27 | Oct 31 | Nov 4 | Nov 9 |
| 28°F | Oct 20 | Oct 27 | Nov 1 | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 20 | Nov 26 |
| 24°F | Nov 1 | Nov 9 | Nov 14 | Nov 18 | Nov 23 | Nov 28 | Dec 3 | Dec 10 | Dec 22 |
| 20°F | Nov 13 | Nov 20 | Nov 27 | Dec 2 | Dec 9 | Dec 16 | Dec 26 | Jan 3 | Jan 26 |
| 16°F | Nov 19 | Nov 28 | Dec 4 | Dec 9 | Dec 15 | Dec 24 | Jan 2 | Jan 15 | 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: Monroe, Wa, about 5 miles away@if(!empty($station['elevation_ft'])), at 120 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 Cathcart, WA?
On average, the last spring frost (32°F) around Cathcart, WA is about Apr 17. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 29.
When is the first frost in the fall?
The first fall frost around Cathcart, WA typically arrives about Oct 23. 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 17 on average, or Mar 29 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 188 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 98296 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026