Lake Oswego, OR 97035 Frost Dates
97035, near Lake Oswego, OR: the frost window
Around 02/11 is the usual last spring frost, about 167 days away. Fall's first freeze usually shows up around 12/05, roughly 303 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Lake Oswego in Zone 9a (20 to 25°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Lake Oswego's growing season runs out in roughly 14 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 02/11 isn't a guarantee
02/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/05 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/26 and only about 1 year in 10 sees frost after that.
Lake Oswego against the rest of the dataset
At roughly 303 frost-free days, Lake Oswego places 3,779 of 40,283 ZIP codes in this dataset. Within OR, it ranks 26 of 463.
Learn more
Two guides worth reading on 97035: zone vs. frost date, on why Zone 9a and Lake Oswego's frost date answer different questions, and the frost range, on how to read the range around Lake Oswego's dates instead of trusting one.