Haswell, CO 80823 Frost Dates
80823, near Haswell, CO: the frost window
Typically, the last spring freeze lands around 05/09, roughly 254 days out. Fall's first freeze usually shows up around 10/06, roughly 149 days after the last spring frost.
Zone 5b (-15 to -10°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Haswell, not a forecast for this year.
Stretching the season past the first frost
Haswell'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.
The actual range around Haswell's last frost
05/09 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/28 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/23 and only about 1 year in 10 sees frost after that.
Haswell against the rest of the dataset
Haswell's growing season runs about 149 days, ranking 35,605 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 340 of 624.
Learn more
Two guides worth reading on 80823: zone vs. frost date, on why Zone 5b and Haswell's frost date answer different questions, and the frost range, on how to read the range around Haswell's dates instead of trusting one.