Umatilla, OR 99346 Frost Dates
99346, near Umatilla, OR: the frost window
The last spring frost here typically falls around 03/27, about 211 days from today. Fall's first freeze usually shows up around 11/04, roughly 221 days after the last spring frost.
Zone 7b (5 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 Umatilla, not a forecast for this year.
Stretching the season past the first frost
Umatilla's growing season runs out in roughly 10 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 03/27 isn't a guarantee
03/27 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/08 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/14 and only about 1 year in 10 sees frost after that.
Umatilla against the rest of the dataset
Umatilla's growing season runs about 221 days, ranking 12,488 of 40,283 US ZIP codes measured here, longest to shortest. Within OR, it ranks 171 of 463.
Learn more
Two guides worth reading on 99346: local microclimates, on what one yard in Umatilla can differ from the 99346 normal, and zone vs. frost date, on why Zone 7b and Umatilla's frost date answer different questions.