Royal City, WA 99357 Frost Dates
Frost dates for Royal City, WA, ZIP 99357
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.
The USDA Plant Hardiness Zone Map puts Royal City in Zone 7a (0 to 5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 7a around Royal City 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 Royal City compares
Royal City's growing season runs about 222 days, ranking 12,272 of 40,283 US ZIP codes measured here, longest to shortest. Within WA, it ranks 238 of 700.
Learn more
the frost range explains how to read the range around Royal City's dates instead of trusting one, and local microclimates explains what one yard in Royal City can differ from the 99357 normal.