Mukilteo, WA 98204 Frost Dates
98204, near Mukilteo, WA: the frost window
Around 03/09 is the usual last spring frost, about 193 days away. Fall's first freeze usually shows up around 11/17, roughly 250 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Mukilteo in Zone 9a (20 to 25°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Mukilteo's growing season runs out in roughly 12 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 03/09 isn't a guarantee
03/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 03/29 and only about 1 year in 10 sees frost after that.
Mukilteo against the rest of the dataset
Mukilteo's growing season runs about 250 days, ranking 7,478 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 98 of 700.
Learn more
Two guides worth reading on 98204: the frost range, on how to read the range around Mukilteo's dates instead of trusting one, and local microclimates, on what one yard in Mukilteo can differ from the 98204 normal.