Frost Dates for 81520 — Clifton, Colorado

Half of springs at Grand Junction 6ESE, CO see their last 32°F night by April 23; only one in ten is past it by April 6, and one in ten still has one after May 9. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 9 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 75% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 20 in half of years, as early as October 5 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 12 days later, around November 1; in spring the one-in-ten date for 28°F is April 25, 14 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, longer than at 98% of the 110 Colorado stations; it reaches 202 days one year in ten and falls short of 157 one year in ten. On average 128 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 10 days longer, to about May 3, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 3 and February 14.

July is the warmest month at Grand Junction 6ESE, CO, averaging 93°F by day and 65°F at night; January is the coldest at 39°F and 19°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 24% of years.

Warmth for growing adds up to 3,760 growing degree days a year (base 50°F), more than at 98% of the 110 Colorado stations. 35% of them (1,300) have built up by the end of June, and July adds the most, 905. Precipitation totals 9.0 inches a year, most in September (1.2") and least in January (0.5"); May to September bring 46% of it.

The nearest other station, Grand Junction WFO, CO, 5 miles northwest of Clifton, has a last frost 9 days earlier (April 14), a first frost 3 days later (October 23), a season 11 days longer.

The first measurable snow (0.1 inch or more) in Clifton usually arrives around November 25, and the last of the season around March 19. Those are the middle dates across the winters of 1991–2020 at Grand Junction 6ESE, CO, 3.2 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 35 days after the last snow.

ZIP 81520 is 3 miles from Grand Junction 6ESE, CO, which stands at 4,760 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 81520 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.