In Seattle, WA, the average last spring frost is Mar 2 and the average first fall frost is Nov 23, which leaves about 266 frost-free days for the garden. These dates come from NOAA climate normals for the Seattle Tacoma International Airport, WA weather station, at 370 feet above sea level.
A very long season allows two full rounds of vegetables. Plant cool-season crops early and again in fall, and plan warm-season crops so they finish before the hottest part of summer. Frost timing varies from year to year: in about 1 spring in 10 the last frost falls as late as Mar 23, and in about 1 fall in 10 the first frost arrives as early as Nov 6.
Frost dates for Seattle, WA
| Chance of a freeze (32°F) after or before this date | Last spring frost | First fall frost | Freeze-free season |
|---|---|---|---|
| Optimistic (about 1 year in 10) | Feb 5 | Dec 15 | 313 days |
| Average (half of years) | Mar 2 | Nov 23 | 266 days |
| Cautious (9 years in 10 are safe) | Mar 23 | Nov 6 | 228 days |
Source: NOAA NCEI U.S. Climate Normals, 1991 to 2020. Use the cautious dates for tender crops such as tomatoes and peppers.
When to plant in Seattle, WA
These windows count weeks forward and back from the average frost dates above. They are planning guides: check the forecast before planting tender crops, and see our what to plant now tool for today's date.
| Crop | Start seeds indoors | Plant outdoors in spring | Plant in fall |
|---|---|---|---|
| Tomatoes | Jan 5 to Jan 19 | Mar 9 to Mar 16 | – |
| Peppers | Dec 22 to Jan 5 | Mar 16 to Mar 23 | – |
| Eggplant | Dec 22 to Jan 5 | Mar 16 to Mar 23 | – |
| Onions | Dec 22 to Jan 5 | Feb 2 to Feb 16 | – |
| Parsley | Dec 22 to Jan 5 | Mar 2 to Mar 9 | – |
| Broccoli, cabbage, cauliflower | Jan 5 to Jan 19 | Feb 16 to Feb 23 | Aug 31 to Sep 28 |
| Basil | Jan 19 to Jan 19 | Mar 9 to Mar 16 | – |
| Peas | Sow outdoors | Jan 19 to Feb 2 | Aug 31 to Sep 28 |
| Spinach | Sow outdoors | Jan 19 to Feb 2 | Sep 28 to Oct 26 |
| Radishes | Sow outdoors | Jan 19 to Feb 2 | Sep 28 to Oct 26 |
| Lettuce | Sow outdoors | Feb 2 to Feb 16 | Sep 28 to Oct 26 |
| Carrots | Sow outdoors | Feb 2 to Feb 16 | Aug 31 to Sep 28 |
| Beets | Sow outdoors | Feb 2 to Feb 16 | Aug 31 to Sep 28 |
| Potatoes | Sow outdoors | Feb 2 to Feb 16 | – |
| Kale | Sow outdoors | Feb 2 to Feb 16 | Aug 31 to Sep 28 |
| Swiss chard | Sow outdoors | Feb 16 to Mar 2 | – |
| Cilantro | Sow outdoors | Feb 16 to Mar 2 | Sep 28 to Oct 26 |
| Dill | Sow outdoors | Mar 2 to Mar 9 | – |
| Bush beans | Sow outdoors | Mar 9 to Mar 16 | Aug 20 to Sep 3 |
| Pole beans | Sow outdoors | Mar 9 to Mar 16 | – |
| Sweet corn | Sow outdoors | Mar 9 to Mar 16 | – |
| Cucumbers | Sow outdoors | Mar 9 to Mar 16 | Aug 10 to Aug 24 |
| Zucchini and summer squash | Sow outdoors | Mar 9 to Mar 16 | Aug 20 to Sep 3 |
| Winter squash | Sow outdoors | Mar 9 to Mar 16 | – |
| Sweet potatoes (slips) | Sow outdoors | Mar 16 to Mar 30 | – |
| Okra | Sow outdoors | Mar 16 to Mar 30 | – |
A dash in the fall column means the crop is not usually planted in fall, or the season is too short.
Overnight lows this week
The National Weather Service forecast shows frost risk on: Thu 19 night (36°F), Fri 20 night (36°F). Cover tender plants before dark on those nights.
| Night | Forecast low | Frost risk |
|---|---|---|
| Sat 14 night | 49°F | No frost expected |
| Sun 15 night | 42°F | No frost expected |
| Mon 16 night | 38°F | No frost expected |
| Tue 17 night | 40°F | No frost expected |
| Wed 18 night | 38°F | No frost expected |
| Thu 19 night | 36°F | Frost possible |
| Fri 20 night | 36°F | Frost possible |
Live forecast for the station location, from the National Weather Service. For your own ZIP code, use our garden weather forecast.
More garden tools for Seattle, WA
- Frost dates by ZIP code for your exact location
- What to plant now, based on today's date
- Garden weather forecast by ZIP code
- Safe transplant date calculator
Frequently asked questions
When is the last frost in Seattle, WA?
The average last spring frost is Mar 2. A late frost as far out as Mar 23 happens in about 1 year in 10, so tender plants such as tomatoes and peppers are safest after that cautious date.
When is the first frost in Seattle, WA?
The average first fall frost is Nov 23. It can arrive as early as Nov 6 in about 1 year in 10, so plan to harvest tender crops before then.
How long is the growing season in Seattle, WA?
The average freeze-free season is about 266 days, between the average last spring frost and the average first fall frost.
Where do these dates come from?
They come from the NOAA 1991 to 2020 U.S. Climate Normals for the Seattle Tacoma International Airport, WA station. Hills, valleys, lakes and city heat can shift frost by a week or more, so compare with neighbors who garden near you.