Frost Dates for 80222 — Denver, Colorado

Half of springs at Cherry Creek Dam, CO see their last 32°F night by May 7; only one in ten is past it by April 26, and one in ten still has one after May 21. Planting tender crops after May 12 leaves a 30% risk of a frost on them, after May 15 20%, and after May 21 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 45% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 8 in half of years, as early as September 25 one year in ten, and holds off past October 19 one year in ten. A hard freeze of 28°F follows 7 days later, around October 15; in spring the one-in-ten date for 28°F is May 10, 11 days before the 32°F one. The freeze-free season lasts 152 days in a typical year, longer than at 65% of the 110 Colorado stations; it reaches 169 days one year in ten and falls short of 133 one year in ten. On average 172 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about May 18, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 8 and March 23.

July is the warmest month at Cherry Creek Dam, CO, averaging 90°F by day and 56°F at night; January is the coldest at 47°F and 17°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 78% of years.

Warmth for growing adds up to 2,800 growing degree days a year (base 50°F), more than at 67% of the 110 Colorado stations. 30% of them (852) have built up by the end of June, and July adds the most, 725.

The nearest other station, Denver Water Dept, CO, 6 miles northwest of Denver and 419 feet lower, has a last frost 7 days earlier (April 30), a first frost 4 days later (October 12), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Denver usually arrives around October 20, and the last of the season around May 2. Those are the middle dates across the winters of 1991–2020 at Denver 5.2 S, CO, 2 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 5 days after the last snow.

ZIP 80222 is 6 miles from Cherry Creek Dam, CO, which stands at 5,647 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 9 other ZIP codes share the station; its figures are presented in full for 80013 (Aurora). The 2023 USDA Plant Hardiness Zone Map lists ZIP 80222 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.