Last spring frost
May 4
Frost Dates for Washington, CA
First fall frost
Nov 4
Growing season
183 days
Hardiness zone
9a
In an average year around Washington, CA, the last spring frost (32°F) is about May 4 and the first fall frost is about Nov 4, giving roughly a 183-day growing season. To be safe most years, wait until Apr 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) | Jun 10 | May 22 | Apr 27 |
| Freeze (32°F) | May 31 | May 4 | Apr 12 |
| Hard (28°F) | May 13 | Apr 16 | Mar 17 |
| Severe (24°F) | Apr 25 | Mar 29 | Feb 10 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 10 | Jun 3 | May 31 | May 27 | May 22 | May 16 | May 11 | May 6 | Apr 27 |
| 32°F | May 31 | May 24 | May 15 | May 9 | May 4 | Apr 29 | Apr 25 | Apr 19 | Apr 12 |
| 28°F | May 13 | May 3 | Apr 28 | Apr 23 | Apr 16 | Apr 12 | Apr 6 | Mar 31 | Mar 17 |
| 24°F | Apr 25 | Apr 15 | Apr 8 | Apr 4 | Mar 29 | Mar 20 | Mar 9 | Feb 28 | Feb 10 |
| 20°F | Apr 6 | Mar 24 | Mar 10 | Feb 28 | Feb 20 | Feb 10 | Jan 27 | Jan 12 | Dec 31 |
| 16°F | Feb 27 | Feb 15 | Feb 4 | Jan 25 | Jan 14 | Jan 8 | Jan 3 | Dec 30 | Dec 18 |
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 28 | Oct 20 | Nov 10 |
| Freeze (32°F) | Oct 12 | Nov 4 | Nov 26 |
| Hard (28°F) | Nov 1 | Nov 23 | Dec 15 |
| Severe (24°F) | Nov 14 | Dec 10 | Jan 15 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 28 | Oct 5 | Oct 11 | Oct 16 | Oct 20 | Oct 24 | Oct 30 | Nov 4 | Nov 10 |
| 32°F | Oct 12 | Oct 20 | Oct 26 | Nov 1 | Nov 4 | Nov 8 | Nov 13 | Nov 18 | Nov 26 |
| 28°F | Nov 1 | Nov 7 | Nov 13 | Nov 17 | Nov 23 | Nov 28 | Dec 2 | Dec 7 | Dec 15 |
| 24°F | Nov 14 | Nov 23 | Dec 1 | Dec 5 | Dec 10 | Dec 16 | Dec 23 | Jan 1 | Jan 15 |
| 20°F | Nov 28 | Dec 7 | Dec 15 | Dec 23 | Dec 31 | Jan 4 | Jan 13 | Jan 25 | Feb 17 |
| 16°F | Dec 11 | Dec 19 | Dec 29 | Jan 1 | Jan 5 | Jan 12 | Jan 20 | Feb 2 | 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: Blue Canyon Ap, Ca, about 10 miles away@if(!empty($station['elevation_ft'])), at 5,276 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 Washington, CA?
On average, the last spring frost (32°F) around Washington, CA is about May 4. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 12.
When is the first frost in the fall?
The first fall frost around Washington, CA typically arrives about Nov 4. 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 May 4 on average, or Apr 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 183 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 95959 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026