Morrison, CO 80470 Frost Dates
When can you plant in Morrison, CO?
Typically, the last spring freeze lands around 06/16, roughly 292 days out. The first fall frost typically arrives around 09/08, about 84 frost-free days later.
The USDA Plant Hardiness Zone Map puts Morrison in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 2 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
06/16 is the middle of 30 years of NOAA records, not a promise. Plant by 06/02 and you're betting against frost in roughly 9 years out of 10. 07/01 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Morrison compares
Morrison's growing season runs about 84 days, ranking 40,007 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 562 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 80470 normal.