Seattle, WA 98104 Frost Dates
Frost dates for Seattle, WA, ZIP 98104
Typically, the last spring freeze lands around 03/13, roughly 197 days out. The first fall frost typically arrives around 11/17, about 247 frost-free days later.
Seattle sits in USDA Zone 9a (20 to 25°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 9a around Seattle has about 12 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 03/13 isn't a guarantee
03/13 is the middle of 30 years of NOAA records, not a promise. Plant by 02/20 and you're betting against frost in roughly 9 years out of 10. 04/01 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Seattle compares
About 247 days separate Seattle's last and first frost, putting it 7,747 of 40,283 ZIP codes nationally. Within WA, it ranks 132 of 700.
Learn more
zone vs. frost date explains why Zone 9a and Seattle's frost date answer different questions, and the frost range explains how to read the range around Seattle's dates instead of trusting one.