Mukilteo, WA 98275 Frost Dates
98275, near Mukilteo, WA: the frost window
Typically, the last spring freeze lands around 03/09, roughly 193 days out. Fall's first freeze usually shows up around 11/17, roughly 250 days after the last spring frost.
Zone 8b (15 to 20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Mukilteo, not a forecast for this year.
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.
How much risk comes with planting early here
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
At roughly 250 frost-free days, Mukilteo places 7,479 of 40,283 ZIP codes in this dataset. Within WA, it ranks 99 of 700.
Learn more
Two guides worth reading on 98275: zone vs. frost date, on why Zone 8b and Mukilteo's frost date answer different questions, and the frost range, on how to read the range around Mukilteo's dates instead of trusting one.