Fort Collins, CO 80524 Frost Dates
Fort Collins, CO: when does the frost end?
Typically, the last spring freeze lands around 05/03, roughly 248 days out. Fall's first freeze usually shows up around 10/06, roughly 154 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Fort Collins in Zone 5b (-15 to -10°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
With roughly 6 weeks until Fort Collins's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Fort Collins's last frost
05/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/21 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/15 and only about 1 year in 10 sees frost after that.
Fort Collins against the rest of the dataset
Fort Collins's growing season runs about 154 days, ranking 34,197 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 257 of 624.
Learn more
Before leaning on 80524's figures: local microclimates explains what one yard in Fort Collins can differ from the 80524 normal, while zone vs. frost date explains why Zone 5b and Fort Collins's frost date answer different questions.