Bothell, WA 98021 Frost Dates
Frost dates for Bothell, WA, ZIP 98021
Typically, the last spring freeze lands around 03/08, roughly 192 days out. The first fall frost typically arrives around 11/23, about 259 frost-free days later.
The USDA Plant Hardiness Zone Map puts Bothell in Zone 8b (15 to 20°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 8b around Bothell has about 12 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
03/08 is the middle of 30 years of NOAA records, not a promise. Plant by 02/13 and you're betting against frost in roughly 9 years out of 10. 03/29 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Bothell compares
About 259 days separate Bothell's last and first frost, putting it 6,553 of 40,283 ZIP codes nationally. Within WA, it ranks 41 of 700.
Learn more
zone vs. frost date explains why Zone 8b and Bothell's frost date answer different questions, and the frost range explains how to read the range around Bothell's dates instead of trusting one.