Renton, WA 98055 Frost Dates
98055, near Renton, WA: the frost window
The last spring frost here typically falls around 03/20, about 204 days from today. Fall's first freeze usually shows up around 11/10, roughly 233 days after the last spring frost.
Renton 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.
Stretching the season past the first frost
Renton's growing season runs out in roughly 11 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 03/20 isn't a guarantee
03/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/08 and only about 1 year in 10 sees frost after that.
Renton against the rest of the dataset
Renton's growing season runs about 233 days, ranking 9,843 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 174 of 700.
Learn more
Two guides worth reading on 98055: local microclimates, on what one yard in Renton can differ from the 98055 normal, and zone vs. frost date, on why Zone 9a and Renton's frost date answer different questions.