Kennewick, WA 99363 Frost Dates
99363, near Kennewick, WA: the frost window
Around 04/07 is the usual last spring frost, about 222 days away. Fall's first freeze usually shows up around 10/22, roughly 199 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Kennewick in Zone 7b (5 to 10°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
Kennewick's growing season runs out in roughly 8 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
04/07 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/20 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/30 and only about 1 year in 10 sees frost after that.
Kennewick against the rest of the dataset
Kennewick's growing season runs about 199 days, ranking 17,986 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 333 of 700.
Learn more
Two guides worth reading on 99363: local microclimates, on what one yard in Kennewick can differ from the 99363 normal, and zone vs. frost date, on why Zone 7b and Kennewick's frost date answer different questions.