Seattle, WA 98122 Frost Dates
Frost dates for Seattle, WA, ZIP 98122
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.
The actual range around Seattle's last frost
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
At roughly 247 frost-free days, Seattle places 7,750 of 40,283 ZIP codes in this dataset. Within WA, it ranks 135 of 700.
Learn more
local microclimates explains what one yard in Seattle can differ from the 98122 normal, and zone vs. frost date explains why Zone 9a and Seattle's frost date answer different questions.