Seneca, OR 97873 Frost Dates
Frost dates for Seneca, OR, ZIP 97873
The last spring frost here typically falls around 05/28, about 273 days from today. The first fall frost typically arrives around 09/18, about 113 frost-free days later.
Zone 5b (-15 to -10°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Seneca, not a forecast for this year.
What to do before the first frost
Zone 5b around Seneca has about 3 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around Seneca's last frost
05/28 is the middle of 30 years of NOAA records, not a promise. Plant by 05/12 and you're betting against frost in roughly 9 years out of 10. 06/15 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Seneca compares
About 113 days separate Seneca's last and first frost, putting it 39,407 of 40,283 ZIP codes nationally. Within OR, it ranks 399 of 463.
Learn more
local microclimates explains what one yard in Seneca can differ from the 97873 normal, and zone vs. frost date explains why Zone 5b and Seneca's frost date answer different questions.