Aspen, CO 81612 Frost Dates
81612, near Aspen, CO: the frost window
Around 05/31 is the usual last spring frost, about 276 days away. Fall's first freeze usually shows up around 09/23, roughly 114 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Aspen in Zone 5a (-20 to -15°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
Aspen's growing season runs out in roughly 4 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
05/31 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/16 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/14 and only about 1 year in 10 sees frost after that.
Aspen against the rest of the dataset
About 114 days separate Aspen's last and first frost, putting it 39,351 of 40,283 ZIP codes nationally. Within CO, it ranks 489 of 624.
Learn more
Two guides worth reading on 81612: the frost range, on how to read the range around Aspen's dates instead of trusting one, and local microclimates, on what one yard in Aspen can differ from the 81612 normal.