Bar Nunn, WY 82602 Frost Dates
Bar Nunn, WY: when does the frost end?
Typically, the last spring freeze lands around 05/10, roughly 255 days out. Fall's first freeze usually shows up around 09/29, roughly 138 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 Bar Nunn, not a forecast for this year.
Stretching the season past the first frost
With roughly 5 weeks until Bar Nunn's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/10 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/24 and only about 1 year in 10 sees frost after that.
Bar Nunn against the rest of the dataset
Bar Nunn's growing season runs about 138 days, ranking 37,390 of 40,283 US ZIP codes measured here, longest to shortest. Within WY, it ranks 36 of 192.
Learn more
Before leaning on 82602's figures: local microclimates explains what one yard in Bar Nunn can differ from the 82602 normal, while zone vs. frost date explains why Zone 5a and Bar Nunn's frost date answer different questions.