Antonito, CO 81129 Frost Dates
81129, near Antonito, CO: the frost window
The last spring frost here typically falls around 05/28, about 273 days from today. Fall's first freeze usually shows up around 09/21, roughly 115 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Antonito 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
Antonito's growing season runs out in roughly 3 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/28 isn't a guarantee
05/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/13 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/11 and only about 1 year in 10 sees frost after that.
Antonito against the rest of the dataset
About 115 days separate Antonito's last and first frost, putting it 39,333 of 40,283 ZIP codes nationally. Within CO, it ranks 487 of 624.
Learn more
Two guides worth reading on 81129: local microclimates, on what one yard in Antonito can differ from the 81129 normal, and zone vs. frost date, on why Zone 5a and Antonito's frost date answer different questions.