Dayton, WA 99328 Frost Dates
Frost dates for Dayton, WA, ZIP 99328
Typically, the last spring freeze lands around 03/27, roughly 211 days out. The first fall frost typically arrives around 10/31, about 219 frost-free days later.
Dayton sits in USDA Zone 7a (0 to 5°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.
What to do before the first frost
Zone 7a around Dayton has about 9 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
03/27 is the middle of 30 years of NOAA records, not a promise. Plant by 03/03 and you're betting against frost in roughly 9 years out of 10. 04/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Dayton compares
Dayton's growing season runs about 219 days, ranking 13,031 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 243 of 700.
Learn more
local microclimates explains what one yard in Dayton can differ from the 99328 normal, and zone vs. frost date explains why Zone 7a and Dayton's frost date answer different questions.