Siletz, OR 97380 Frost Dates
97380, near Siletz, OR: the frost window
Around 03/12 is the usual last spring frost, about 196 days away. Fall's first freeze usually shows up around 12/10, roughly 271 days after the last spring frost.
Zone 9a (20 to 25°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 Siletz, not a forecast for this year.
Stretching the season past the first frost
Siletz's growing season runs out in roughly 15 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
03/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 01/24 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/16 and only about 1 year in 10 sees frost after that.
Siletz against the rest of the dataset
About 271 days separate Siletz's last and first frost, putting it 5,457 of 40,283 ZIP codes nationally. Within OR, it ranks 37 of 463.
Learn more
Two guides worth reading on 97380: local microclimates, on what one yard in Siletz can differ from the 97380 normal, and zone vs. frost date, on why Zone 9a and Siletz's frost date answer different questions.