Portland, OR 97203 Frost Dates
Frost dates for Portland, OR, ZIP 97203
Around 03/29 is the usual last spring frost, about 213 days away. The first fall frost typically arrives around 11/09, about 223 frost-free days later.
Zone 9a (20 to 25°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Portland, not a forecast for this year.
What to do before the first frost
Zone 9a around Portland 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.
How much risk comes with planting early here
03/29 is the middle of 30 years of NOAA records, not a promise. Plant by 03/06 and you're betting against frost in roughly 9 years out of 10. 04/18 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Portland compares
About 223 days separate Portland's last and first frost, putting it 11,987 of 40,283 ZIP codes nationally. Within OR, it ranks 158 of 463.
Learn more
the frost range explains how to read the range around Portland's dates instead of trusting one, and local microclimates explains what one yard in Portland can differ from the 97203 normal.