Hermiston, OR 97838 Frost Dates
Hermiston, OR: when does the frost end?
Around 04/26 is the usual last spring frost, about 241 days away. Fall's first freeze usually shows up around 10/10, roughly 167 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Hermiston in Zone 7b (5 to 10°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 6 weeks until Hermiston's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/26 isn't a guarantee
04/26 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/09 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/10 and only about 1 year in 10 sees frost after that.
Hermiston against the rest of the dataset
About 167 days separate Hermiston's last and first frost, putting it 29,889 of 40,283 ZIP codes nationally. Within OR, it ranks 321 of 463.
Learn more
Before leaning on 97838's figures: zone vs. frost date explains why Zone 7b and Hermiston's frost date answer different questions, while the frost range explains how to read the range around Hermiston's dates instead of trusting one.