Bairoil, WY 82620 Frost Dates
Frost dates for Bairoil, WY, ZIP 82620
Around 05/09 is the usual last spring frost, about 254 days away. The first fall frost typically arrives around 10/07, about 148 frost-free days later.
Bairoil sits in USDA Zone 5a (-20 to -15°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.
What to do before the first frost
Zone 5a around Bairoil has about 6 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
05/09 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 05/23 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Bairoil compares
Bairoil's growing season runs about 148 days, ranking 35,817 of 40,283 US ZIP codes measured here, longest to shortest. Within WY, it ranks 9 of 192.
Learn more
local microclimates explains what one yard in Bairoil can differ from the 82620 normal, and zone vs. frost date explains why Zone 5a and Bairoil's frost date answer different questions.