Louisville, CO 80027 Frost Dates
Louisville, CO: when does the frost end?
Around 05/06 is the usual last spring frost, about 251 days away. Fall's first freeze usually shows up around 10/05, roughly 151 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Louisville in Zone 6a (-10 to -5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 5 weeks until Louisville's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/06 isn't a guarantee
05/06 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/24 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/18 and only about 1 year in 10 sees frost after that.
Louisville against the rest of the dataset
Louisville's growing season runs about 151 days, ranking 34,954 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 311 of 624.
Learn more
Before leaning on 80027's figures: zone vs. frost date explains why Zone 6a and Louisville's frost date answer different questions, while the frost range explains how to read the range around Louisville's dates instead of trusting one.