Arco, ID 83213 Frost Dates
83213, near Arco, ID: the frost window
The last spring frost here typically falls around 05/22, about 267 days from today. Fall's first freeze usually shows up around 09/22, roughly 119 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 Arco, not a forecast for this year.
Stretching the season past the first frost
Arco'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.
How much risk comes with planting early here
05/22 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/05 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/09 and only about 1 year in 10 sees frost after that.
Arco against the rest of the dataset
Arco's growing season runs about 119 days, ranking 39,154 of 40,283 US ZIP codes measured here, longest to shortest. Within ID, it ranks 219 of 320.
Learn more
Two guides worth reading on 83213: local microclimates, on what one yard in Arco can differ from the 83213 normal, and zone vs. frost date, on why Zone 5a and Arco's frost date answer different questions.