Franklin, ID 83237 Frost Dates
83237, near Franklin, ID: the frost window
Typically, the last spring freeze lands around 05/16, roughly 261 days out. Fall's first freeze usually shows up around 09/28, roughly 133 days after the last spring frost.
Zone 6a (-10 to -5°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 Franklin, not a forecast for this year.
Stretching the season past the first frost
Franklin's growing season runs out in roughly 4 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 Franklin's last frost
05/16 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/04 and only about 1 year in 10 sees frost after that.
Franklin against the rest of the dataset
About 133 days separate Franklin's last and first frost, putting it 38,078 of 40,283 ZIP codes nationally. Within ID, it ranks 161 of 320.
Learn more
Two guides worth reading on 83237: local microclimates, on what one yard in Franklin can differ from the 83237 normal, and zone vs. frost date, on why Zone 6a and Franklin's frost date answer different questions.