Harrisburg, OR 97446 Frost Dates
Frost dates for Harrisburg, OR, ZIP 97446
Around 04/11 is the usual last spring frost, about 226 days away. The first fall frost typically arrives around 10/23, about 196 frost-free days later.
Harrisburg sits in USDA Zone 8b (15 to 20°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 8b around Harrisburg has about 8 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 Harrisburg's last frost
04/11 is the middle of 30 years of NOAA records, not a promise. Plant by 03/15 and you're betting against frost in roughly 9 years out of 10. 05/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Harrisburg compares
At roughly 196 frost-free days, Harrisburg places 18,974 of 40,283 ZIP codes in this dataset. Within OR, it ranks 250 of 463.
Learn more
local microclimates explains what one yard in Harrisburg can differ from the 97446 normal, and zone vs. frost date explains why Zone 8b and Harrisburg's frost date answer different questions.