Portland, OR 97217 Frost Dates
Portland, OR: when does the frost end?
Around 03/29 is the usual last spring frost, about 213 days away. Fall's first freeze usually shows up around 11/09, roughly 223 days after the last spring frost.
Portland sits in USDA Zone 9a (20 to 25°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.
Stretching the season past the first frost
With roughly 10 weeks until Portland's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 03/29 isn't a guarantee
03/29 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/06 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/18 and only about 1 year in 10 sees frost after that.
Portland against the rest of the dataset
Portland's growing season runs about 223 days, ranking 11,989 of 40,283 US ZIP codes measured here, longest to shortest. Within OR, it ranks 160 of 463.
Learn more
Before leaning on 97217's figures: zone vs. frost date explains why Zone 9a and Portland's frost date answer different questions, while the frost range explains how to read the range around Portland's dates instead of trusting one.