Union, OR 97883 Frost Dates
97883, near Union, OR: the frost window
Around 05/11 is the usual last spring frost, about 256 days away. Fall's first freeze usually shows up around 09/26, roughly 136 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Union in Zone 6b (-5 to 0°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
Union's growing season runs out in roughly 4 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Union's last frost
05/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/26 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/31 and only about 1 year in 10 sees frost after that.
Union against the rest of the dataset
At roughly 136 frost-free days, Union places 37,701 of 40,283 ZIP codes in this dataset. Within OR, it ranks 381 of 463.
Learn more
Two guides worth reading on 97883: zone vs. frost date, on why Zone 6b and Union's frost date answer different questions, and the frost range, on how to read the range around Union's dates instead of trusting one.