Seattle, WA Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Seattle, Washington.
Gardening in Seattle
Seattle gardeners have a secret the rest of the country doesn't understand: this is one of the best food-growing climates in America. The maritime mildness that makes people complain about gray skies also means you can grow cool-season crops for 9 months of the year. Your kale doesn't know what month it is, and it doesn't care.
The famous rain is real from October through June, but here's what outsiders don't know: Seattle summers are dry. July and August often go weeks without rain, meaning your summer garden needs irrigation despite the city's wet reputation. The marine air keeps temperatures moderate — rarely above 85°F, rarely below 25°F — creating a year-round growing window that Minnesota and Arizona gardeners can only dream about.
Seahawks fans know about building something great in conditions everyone else underestimates. Pike Place Market sets the standard for what local food looks like, and Seattle's P-Patch community garden program — the nation's oldest — has been turning neighborhoods into growing communities since 1973. Your overachieving neighbor's garden isn't showing off. It's just what happens when you garden in this climate.
What This Means for Seattle Gardeners
The average last spring frost in Seattle is around March 5, and the average first fall frost arrives around November 15. That gives you approximately 255 frost-free days to work with.
That's a generous season. You have time for full-size tomatoes, long-season peppers, and even watermelons without the anxiety of racing the frost. Start warm-season seeds indoors 6-8 weeks before your last frost to hit the ground running. Fall planting is your second opportunity — garlic, kale, lettuce, and broccoli all go in 8-10 weeks before your first frost for harvest into late autumn.
These dates are based on NOAA 30-year Climate Normal data for the Seattle area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Seattle
Seattle's 255-day growing season is generous — long enough for two full growing windows (spring and fall) with warm-season crops between them. You can grow the full range of vegetables, herbs, and flowers with proper timing. Focus on heat-tolerant varieties for midsummer and cool-season crops for extended fall harvests. Recommended starting points: tomatoes, peppers, beans, cucumbers, squash, garlic, kale, and sunflowers.
See the full Washington planting guide for all 40 plants: Washington Planting Calendar. Or enter your zip code for exact planting dates personalized to Seattle.
More About Zone 8B
Seattle is in USDA Hardiness Zone 8B, which means average annual extreme minimum temperatures between 15°F to 20°F. View the full Zone 8B planting guide.
See the complete planting calendar for Washington: Washington Planting Calendar.
Other Cities in Washington
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Seattle area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Seattle (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Cool-season crops go in 3-4 weeks before your last frost (March 5). Warm-season crops wait until 2 weeks after. You have time for a fall round too — plant cool-season crops again in late summer for harvest into autumn. Enter your zip code for exact dates.