Burien, WA 98146 Frost Dates
98146, near Burien, WA: the frost window
Typically, the last spring freeze lands around 03/13, roughly 197 days out. Fall's first freeze usually shows up around 11/17, roughly 247 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Burien 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
Burien'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.
The actual range around Burien's last frost
03/13 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/20 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/01 and only about 1 year in 10 sees frost after that.
Burien against the rest of the dataset
About 247 days separate Burien's last and first frost, putting it 7,779 of 40,283 ZIP codes nationally. Within WA, it ranks 147 of 700.
Learn more
Two guides worth reading on 98146: local microclimates, on what one yard in Burien can differ from the 98146 normal, and zone vs. frost date, on why Zone 9a and Burien's frost date answer different questions.