Iliff, CO 80745 Frost Dates
Frost dates for Iliff, CO, ZIP 80745
Typically, the last spring freeze lands around 05/15, roughly 260 days out. The first fall frost typically arrives around 09/30, about 135 frost-free days later.
Iliff 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.
What to do before the first frost
Zone 5b around Iliff has about 5 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around Iliff's last frost
05/15 is the middle of 30 years of NOAA records, not a promise. Plant by 05/04 and you're betting against frost in roughly 9 years out of 10. 05/30 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Iliff compares
Iliff's growing season runs about 135 days, ranking 37,918 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 428 of 624.
Learn more
the frost range explains how to read the range around Iliff's dates instead of trusting one, and local microclimates explains what one yard in Iliff can differ from the 80745 normal.