Basalt, ID 83218 Frost Dates
When can you plant in Basalt, ID?
Typically, the last spring freeze lands around 05/05, roughly 250 days out. The first fall frost typically arrives around 10/03, about 149 frost-free days later.
Zone 5b (-15 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 Basalt, not a forecast for this year.
What to do before the first frost
About 5 weeks of growing season left in Basalt before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Basalt's last frost
05/05 is the middle of 30 years of NOAA records, not a promise. Plant by 04/23 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Basalt compares
Basalt's growing season runs about 149 days, ranking 35,566 of 40,283 US ZIP codes measured here, longest to shortest. Within ID, it ranks 122 of 320.
Learn more
local microclimates covers what one yard in Basalt can differ from the 83218 normal. zone vs. frost date covers why Zone 5b and Basalt's frost date answer different questions.