Simla, CO 80830 Frost Dates
80830, near Simla, CO: the frost window
Typically, the last spring freeze lands around 05/12, roughly 257 days out. Fall's first freeze usually shows up around 10/02, roughly 141 days after the last spring frost.
Simla sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Simla's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Simla's last frost
05/12 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Simla against the rest of the dataset
Simla's growing season runs about 141 days, ranking 36,958 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 401 of 624.
Learn more
Two guides worth reading on 80830: zone vs. frost date, on why Zone 5b and Simla's frost date answer different questions, and the frost range, on how to read the range around Simla's dates instead of trusting one.