Ontario, OR 97914 Frost Dates
97914, near Ontario, OR: the frost window
Typically, the last spring freeze lands around 04/21, roughly 236 days out. Fall's first freeze usually shows up around 10/14, roughly 176 days after the last spring frost.
Ontario sits in USDA Zone 7a (0 to 5°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.
Stretching the season past the first frost
Ontario's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/21 isn't a guarantee
04/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/04 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/08 and only about 1 year in 10 sees frost after that.
Ontario against the rest of the dataset
At roughly 176 frost-free days, Ontario places 26,403 of 40,283 ZIP codes in this dataset. Within OR, it ranks 307 of 463.
Learn more
Two guides worth reading on 97914: the frost range, on how to read the range around Ontario's dates instead of trusting one, and local microclimates, on what one yard in Ontario can differ from the 97914 normal.