Kennewick, WA 99336 Frost Dates
Kennewick, WA: when does the frost end?
Typically, the last spring freeze lands around 03/28, roughly 212 days out. Fall's first freeze usually shows up around 10/30, roughly 216 days after the last spring frost.
Kennewick sits in USDA Zone 7b (5 to 10°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
With roughly 9 weeks until Kennewick's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Kennewick's last frost
03/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/09 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/10 and only about 1 year in 10 sees frost after that.
Kennewick against the rest of the dataset
Kennewick's growing season runs about 216 days, ranking 13,702 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 251 of 700.
Learn more
Before leaning on 99336's figures: local microclimates explains what one yard in Kennewick can differ from the 99336 normal, while zone vs. frost date explains why Zone 7b and Kennewick's frost date answer different questions.