Donnelly, ID 83615 Frost Dates
83615, near Donnelly, ID: the frost window
Typically, the last spring freeze lands around 05/30, roughly 275 days out. Fall's first freeze usually shows up around 09/19, roughly 110 days after the last spring frost.
Zone 5a (-20 to -15°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 Donnelly, not a forecast for this year.
Stretching the season past the first frost
Donnelly's growing season runs out in roughly 3 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Donnelly's last frost
05/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/10 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/21 and only about 1 year in 10 sees frost after that.
Donnelly against the rest of the dataset
At roughly 110 frost-free days, Donnelly places 39,515 of 40,283 ZIP codes in this dataset. Within ID, it ranks 240 of 320.
Learn more
Two guides worth reading on 83615: local microclimates, on what one yard in Donnelly can differ from the 83615 normal, and zone vs. frost date, on why Zone 5a and Donnelly's frost date answer different questions.