Morrison, CO 80034 Frost Dates
When can you plant in Morrison, CO?
Around 05/08 is the usual last spring frost, about 253 days away. The first fall frost typically arrives around 10/03, about 147 frost-free days later.
The USDA Plant Hardiness Zone Map puts Morrison in Zone 6a (-10 to -5°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 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
About 147 days separate Morrison's last and first frost, putting it 35,966 of 40,283 ZIP codes nationally. Within CO, it ranks 353 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 80034 normal.