Frost Dates for 86021 — Colorado City, Arizona

Half of springs at Colorado City, AZ see their last 32°F night by April 26; only one in ten is past it by April 6, and one in ten still has one after May 15. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 8 20%, and after May 15 10%. The 19 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 98 Arizona stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 25 in half of years, as early as October 11 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 11 days later, around November 5; in spring the one-in-ten date for 28°F is May 2, 13 days before the 32°F one. The freeze-free season lasts 180 days in a typical year, shorter than at 76% of the 98 Arizona stations; it reaches 205 days one year in ten and falls short of 157 one year in ten. On average 120 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 12 days longer, to about May 8, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 4 and February 7.

July is the warmest month at Colorado City, AZ, averaging 95°F by day and 62°F at night; December is the coldest at 48°F and 24°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 38% of years.

Warmth for growing adds up to 3,812 growing degree days a year (base 50°F), fewer than at 75% of the 102 Arizona stations. 32% of them (1,233) have built up by the end of June, and July adds the most, 872. Precipitation totals 14.3 inches a year, most in February (1.8") and least in June (0.3"); May to September bring 35% of it.

The nearest other station, La Verkin, UT, 22 miles northwest of Colorado City and 1,807 feet lower, has a last frost 25 days earlier (April 1), a first frost 11 days later (November 5), a season 37 days longer.

The first measurable snow (0.1 inch or more) in Colorado City usually arrives around December 18, and the last of the season around March 18. Those are the middle dates across the winters of 1991–2020 at Colorado City, AZ, 0.7 miles away: half of years saw snow earlier, half later. Snow fell in 90% of those winters. The last 32°F night of spring typically comes 39 days after the last snow.

ZIP 86021 is under a mile from Colorado City, AZ, which stands at 5,001 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 86021 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.