Last spring frost
Mar 28
Frost Dates for Concrete, WA
First fall frost
Nov 14
Growing season
229 days
Hardiness zone
8a
In an average year around Concrete, WA, the last spring frost (32°F) is about Mar 28 and the first fall frost is about Nov 14, giving roughly a 229-day growing season. To be safe most years, wait until Mar 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) | May 11 | Apr 25 | Apr 5 |
| Freeze (32°F) | Apr 19 | Mar 28 | Mar 7 |
| Hard (28°F) | Mar 20 | Feb 25 | Jan 19 |
| Severe (24°F) | Feb 28 | Jan 27 | Dec 13 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 11 | May 6 | May 2 | Apr 29 | Apr 25 | Apr 21 | Apr 17 | Apr 12 | Apr 5 |
| 32°F | Apr 19 | Apr 10 | Apr 5 | Apr 1 | Mar 28 | Mar 23 | Mar 18 | Mar 13 | Mar 7 |
| 28°F | Mar 20 | Mar 11 | Mar 6 | Mar 1 | Feb 25 | Feb 20 | Feb 14 | Feb 4 | Jan 19 |
| 24°F | Feb 28 | Feb 22 | Feb 13 | Feb 3 | Jan 27 | Jan 18 | Jan 9 | Dec 31 | Dec 13 |
| 20°F | Feb 19 | Feb 2 | Jan 26 | Jan 18 | Jan 9 | Jan 1 | Dec 23 | Dec 10 | Dec 5 |
| 16°F | Jan 29 | Jan 20 | Jan 12 | Jan 6 | Jan 1 | Dec 24 | Dec 11 | Dec 6 | Dec 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) | Oct 8 | Oct 25 | Nov 13 |
| Freeze (32°F) | Oct 23 | Nov 14 | Dec 4 |
| Hard (28°F) | Nov 10 | Dec 2 | Jan 3 |
| Severe (24°F) | Nov 23 | Dec 20 | Feb 1 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 8 | Oct 15 | Oct 19 | Oct 22 | Oct 25 | Oct 29 | Nov 1 | Nov 6 | Nov 13 |
| 32°F | Oct 23 | Oct 31 | Nov 5 | Nov 9 | Nov 14 | Nov 19 | Nov 23 | Nov 27 | Dec 4 |
| 28°F | Nov 10 | Nov 16 | Nov 23 | Nov 27 | Dec 2 | Dec 6 | Dec 13 | Dec 21 | Jan 3 |
| 24°F | Nov 23 | Nov 30 | Dec 6 | Dec 11 | Dec 20 | Dec 29 | Jan 3 | Jan 14 | Feb 1 |
| 20°F | Nov 28 | Dec 5 | Dec 9 | Dec 18 | Dec 28 | Jan 2 | Jan 11 | Jan 23 | Feb 1 |
| 16°F | Nov 28 | Dec 4 | Dec 7 | Dec 14 | Dec 26 | Jan 1 | Jan 6 | Jan 14 | Jan 25 |
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: Concrete Ppl Fish Stn, Wa, about 1.5 miles away@if(!empty($station['elevation_ft'])), at 195 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 Concrete, WA?
On average, the last spring frost (32°F) around Concrete, WA is about Mar 28. In cooler years it can run later, so for a safer bet many gardeners wait until Mar 7.
When is the first frost in the fall?
The first fall frost around Concrete, WA typically arrives about Nov 14. 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 28 on average, or Mar 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 229 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 98237 Planting calendar → Washington frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026