Hartman, CO 81043 Frost Dates
81043, near Hartman, CO: the frost window
Typically, the last spring freeze lands around 05/01, roughly 246 days out. Fall's first freeze usually shows up around 10/12, roughly 163 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Hartman 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
Hartman's growing season runs out in roughly 6 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
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Hartman against the rest of the dataset
Hartman's growing season runs about 163 days, ranking 31,555 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 72 of 624.
Learn more
Two guides worth reading on 81043: local microclimates, on what one yard in Hartman can differ from the 81043 normal, and zone vs. frost date, on why Zone 6a and Hartman's frost date answer different questions.