Jefferson, OR 97352 Frost Dates
Jefferson, OR: when does the frost end?
Typically, the last spring freeze lands around 04/17, roughly 232 days out. Fall's first freeze usually shows up around 10/28, roughly 194 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Jefferson in Zone 8b (15 to 20°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
With roughly 9 weeks until Jefferson's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/17 isn't a guarantee
04/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/08 and only about 1 year in 10 sees frost after that.
Jefferson against the rest of the dataset
About 194 days separate Jefferson's last and first frost, putting it 19,487 of 40,283 ZIP codes nationally. Within OR, it ranks 259 of 463.
Learn more
Before leaning on 97352's figures: local microclimates explains what one yard in Jefferson can differ from the 97352 normal, while zone vs. frost date explains why Zone 8b and Jefferson's frost date answer different questions.