Westminster, CO 80021 Frost Dates
When can you plant in Westminster, CO?
Around 05/02 is the usual last spring frost, about 247 days away. The first fall frost typically arrives around 10/11, about 160 frost-free days later.
The USDA Plant Hardiness Zone Map puts Westminster 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 6 weeks of growing season left in Westminster 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
05/02 is the middle of 30 years of NOAA records, not a promise. Plant by 04/18 and you're betting against frost in roughly 9 years out of 10. 05/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Westminster compares
Westminster's growing season runs about 160 days, ranking 32,191 of 40,283 US ZIP codes measured here, longest to shortest. Within CO, it ranks 87 of 624.
Learn more
local microclimates covers what one yard in Westminster can differ from the 80021 normal. zone vs. frost date covers why Zone 6a and Westminster's frost date answer different questions.