Morrison, CO 80162 Frost Dates
When can you plant in Morrison, CO?
Typically, the last spring freeze lands around 05/08, roughly 253 days out. The first fall frost typically arrives around 10/03, about 147 frost-free days later.
Morrison sits in USDA Zone 6a (-10 to -5°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
About 5 weeks of growing season left in Morrison before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
05/08 is the middle of 30 years of NOAA records, not a promise. Plant by 04/27 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Morrison compares
Morrison's growing season runs about 147 days, ranking 35,967 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 354 of 624.
Learn more
the frost range covers how to read the range around Morrison's dates instead of trusting one. local microclimates covers what one yard in Morrison can differ from the 80162 normal.