Mattawa, WA 98950 Frost Dates
Frost dates for Mattawa, WA, ZIP 98950
Around 03/24 is the usual last spring frost, about 208 days away. The first fall frost typically arrives around 11/04, about 222 frost-free days later.
Mattawa 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 Mattawa has about 10 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.
Why 03/24 isn't a guarantee
03/24 is the middle of 30 years of NOAA records, not a promise. Plant by 03/04 and you're betting against frost in roughly 9 years out of 10. 04/07 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Mattawa compares
About 222 days separate Mattawa's last and first frost, putting it 12,258 of 40,283 ZIP codes nationally. Within WA, it ranks 235 of 700.
Learn more
the frost range explains how to read the range around Mattawa's dates instead of trusting one, and local microclimates explains what one yard in Mattawa can differ from the 98950 normal.