When Is the Last Frost in Washington?
The average last spring frost in Washington falls between March 8 and May 13 for most ZIP codes, with a statewide median of April 15. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Seattle | Mar 13 | Apr 1 | Nov 17 | 247 days |
| Spokane | Apr 26 | May 10 | Oct 12 | 168 days |
| Tacoma | Mar 8 | Mar 31 | Nov 14 | 250 days |
| Vancouver | Mar 29 | Apr 18 | Nov 9 | 223 days |
| Bellevue | Mar 8 | Mar 29 | Nov 23 | 259 days |
| Kent | Mar 20 | Apr 8 | Nov 10 | 233 days |
| Everett | Mar 24 | Apr 11 | Nov 2 | 223 days |
| Spokane Valley | Apr 26 | May 10 | Oct 15 | 170 days |
| Renton | Mar 13 | Mar 31 | Nov 16 | 248 days |
| Federal Way | Mar 8 | Mar 31 | Nov 14 | 250 days |
| Yakima | Apr 8 | Apr 28 | Oct 23 | 196 days |
| Bellingham | Apr 1 | Apr 24 | Nov 2 | 216 days |
| Kennewick | Mar 28 | Apr 10 | Oct 30 | 216 days |
| Lacey | Apr 29 | May 15 | Oct 14 | 169 days |
| Bremerton | Mar 29 | Apr 24 | Nov 14 | 227 days |
| Longview | Apr 8 | May 2 | Nov 5 | 210 days |
| Wenatchee | Apr 4 | Apr 19 | Oct 28 | 208 days |
| Mount Vernon | Mar 24 | Apr 14 | Nov 3 | 224 days |
| Pullman | May 6 | May 25 | Sep 29 | 143 days |
| Tumwater | Apr 29 | May 15 | Oct 14 | 169 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 154 Washington weather stations with frost records, median last frost dates run from February 26 at Olga 2 SE, WA to June 6 at Davenport, WA. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in Washington?
The average first fall frost in Washington arrives between September 28 and November 21 for most ZIP codes, with a median of October 25. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Seattle has a 10% chance of frost before November 1, Spokane has a 10% chance of frost before September 29 and Tacoma has a 10% chance of frost before October 30. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in Washington?
Transplant tomatoes in Washington 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: Mar 20 – Mar 27 in Seattle, May 3 – May 10 in Spokane and Mar 15 – Mar 22 in Tacoma. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Seattle | Jan 16 – Jan 30 | Mar 20 – Mar 27 | after Apr 1 |
| Spokane | Mar 1 – Mar 15 | May 3 – May 10 | after May 10 |
| Tacoma | Jan 11 – Jan 25 | Mar 15 – Mar 22 | after Mar 31 |
| Vancouver | Feb 1 – Feb 15 | Apr 5 – Apr 12 | after Apr 18 |
| Bellevue | Jan 11 – Jan 25 | Mar 15 – Mar 22 | after Mar 29 |
| Kent | Jan 23 – Feb 6 | Mar 27 – Apr 3 | after Apr 8 |
| Everett | Jan 27 – Feb 10 | Mar 31 – Apr 7 | after Apr 11 |
| Spokane Valley | Mar 1 – Mar 15 | May 3 – May 10 | after May 10 |
| Renton | Jan 16 – Jan 30 | Mar 20 – Mar 27 | after Mar 31 |
| Federal Way | Jan 11 – Jan 25 | Mar 15 – Mar 22 | after Mar 31 |
| Yakima | Feb 11 – Feb 25 | Apr 15 – Apr 22 | after Apr 28 |
| Bellingham | Feb 4 – Feb 18 | Apr 8 – Apr 15 | after Apr 24 |
| Kennewick | Jan 31 – Feb 14 | Apr 4 – Apr 11 | after Apr 10 |
| Lacey | Mar 4 – Mar 18 | May 6 – May 13 | after May 15 |
| Bremerton | Feb 1 – Feb 15 | Apr 5 – Apr 12 | after Apr 24 |
| Longview | Feb 11 – Feb 25 | Apr 15 – Apr 22 | after May 2 |
| Wenatchee | Feb 7 – Feb 21 | Apr 11 – Apr 18 | after Apr 19 |
| Mount Vernon | Jan 27 – Feb 10 | Mar 31 – Apr 7 | after Apr 14 |
| Pullman | Mar 11 – Mar 25 | May 13 – May 20 | after May 25 |
| Tumwater | Mar 4 – Mar 18 | May 6 – May 13 | after May 15 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Seattle and When?
Seattle's average last frost of March 13 anchors its spring planting calendar: peas and spinach go in from January 30, broccoli and lettuce transplants from February 13, and tomatoes, peppers and squash after March 20.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Jan 30 – Feb 13direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Jan 30 – Feb 20direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Feb 6 – Feb 20direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Feb 13 – Feb 27plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Feb 13 – Feb 27plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Jan 16 – Jan 30 | Feb 13 – Feb 27transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Jan 30 – Feb 13 | Feb 13 – Feb 27transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Feb 13 – Feb 27direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Feb 20 – Feb 27direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Jan 16 – Jan 30 | Mar 20 – Mar 27transplant, 1–2 weeks after last frost | tender |
| Basil | Jan 16 – Jan 30 | Mar 20 – Apr 3transplant, 1–3 weeks after last frost | tender |
| Peppers | Jan 2 – Jan 16 | Mar 27 – Apr 3transplant, 2–3 weeks after last frost | tender |
| Eggplant | Jan 2 – Jan 16 | Mar 27 – Apr 3transplant, 2–3 weeks after last frost | tender |
| Green beans | — | Mar 20 – Apr 3direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | Mar 20 – Apr 3direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Feb 13 – Feb 20 | Mar 20 – Apr 3transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Feb 13 – Feb 20 | Mar 20 – Apr 3transplant, 1–3 weeks after last frost | tender |
| Watermelon | Feb 13 – Feb 20 | Mar 27 – Apr 3transplant, 2–3 weeks after last frost | tender |
Dates for Seattle (last frost Mar 13, NOAA station Seattle Boeing Fld, WA, 6 miles from ZIP 98121). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in Washington?
The frost-free growing season in Washington lasts about 137 to 254 days for most ZIP codes, with a median of 193 days. Among the listed cities, Pullman has the shortest season at 143 days and Bellevue the longest at 259.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in Washington range from 94 days at Davenport, WA to 276 days at Olga 2 SE, WA. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in Washington?
Washington spans USDA hardiness zones 6a to 9b, with zone 8b the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The Washington planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in Washington?
- The average last spring frost in Washington falls between March 8 and May 13 for most ZIP codes, with a statewide median of April 15. Among major cities it ranges from March 8 in Tacoma to May 6 in Pullman.
- When is the last frost in Seattle, Washington?
- Seattle's average last spring frost is March 13, and by April 1 the chance of a later frost drops to 10%. Its first fall frost averages November 17, giving a 247-day growing season (NOAA station Seattle Boeing Fld, WA).
- When should you plant tomatoes in Washington?
- Transplant tomatoes in Washington 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: Mar 20 – Mar 27 in Seattle, May 3 – May 10 in Spokane and Mar 15 – Mar 22 in Tacoma. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in Washington?
- The average first fall frost in Washington arrives between September 28 and November 21 for most ZIP codes, with a median of October 25. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in Washington?
- The frost-free growing season in Washington lasts about 137 to 254 days for most ZIP codes, with a median of 193 days, from 143 days in Pullman to 259 days in Bellevue.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.