Last spring frost
Apr 29
Frost Dates for Colton, WA
First fall frost
Oct 2
Growing season
159 days
Hardiness zone
7a
In an average year around Colton, WA, the last spring frost (32°F) is about Apr 29 and the first fall frost is about Oct 2, giving roughly a 159-day growing season. To be safe most years, wait until Apr 7 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 14 | May 18 | May 2 |
| Freeze (32°F) | May 14 | Apr 29 | Apr 7 |
| Hard (28°F) | Apr 27 | Apr 3 | Mar 9 |
| Severe (24°F) | Apr 4 | Mar 10 | Feb 15 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 14 | Jun 4 | May 28 | May 22 | May 18 | May 14 | May 11 | May 6 | May 2 |
| 32°F | May 14 | May 8 | May 5 | May 1 | Apr 29 | Apr 25 | Apr 21 | Apr 15 | Apr 7 |
| 28°F | Apr 27 | Apr 20 | Apr 15 | Apr 9 | Apr 3 | Mar 30 | Mar 24 | Mar 17 | Mar 9 |
| 24°F | Apr 4 | Mar 27 | Mar 20 | Mar 14 | Mar 10 | Mar 6 | Mar 2 | Feb 25 | Feb 15 |
| 20°F | Mar 16 | Mar 8 | Mar 4 | Feb 28 | Feb 23 | Feb 17 | Feb 10 | Feb 3 | Jan 22 |
| 16°F | Mar 8 | Mar 1 | Feb 24 | Feb 16 | Feb 9 | Feb 2 | Jan 27 | Jan 16 | Jan 2 |
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) | Aug 28 | Sep 19 | Oct 5 |
| Freeze (32°F) | Sep 17 | Oct 2 | Oct 25 |
| Hard (28°F) | Sep 29 | Oct 18 | Nov 15 |
| Severe (24°F) | Oct 9 | Nov 2 | Nov 29 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Aug 28 | Sep 4 | Sep 9 | Sep 14 | Sep 19 | Sep 22 | Sep 26 | Oct 1 | Oct 5 |
| 32°F | Sep 17 | Sep 23 | Sep 27 | Sep 30 | Oct 2 | Oct 6 | Oct 10 | Oct 16 | Oct 25 |
| 28°F | Sep 29 | Oct 4 | Oct 8 | Oct 14 | Oct 18 | Oct 23 | Oct 30 | Nov 4 | Nov 15 |
| 24°F | Oct 9 | Oct 18 | Oct 24 | Oct 30 | Nov 2 | Nov 9 | Nov 15 | Nov 23 | Nov 29 |
| 20°F | Oct 22 | Nov 1 | Nov 8 | Nov 15 | Nov 21 | Nov 25 | Nov 30 | Dec 6 | Dec 14 |
| 16°F | Nov 3 | Nov 14 | Nov 24 | Nov 29 | Dec 3 | Dec 9 | Dec 15 | Dec 22 | Jan 5 |
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: Pullman Moscow Rgnl Ap, Wa, about 11.8 miles away@if(!empty($station['elevation_ft'])), at 2,551 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 Colton, WA?
On average, the last spring frost (32°F) around Colton, WA is about Apr 29. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 7.
When is the first frost in the fall?
The first fall frost around Colton, WA typically arrives about Oct 2. 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 29 on average, or Apr 7 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 159 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 99113 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026