Frost Dates for 80610 — Ault, Colorado

Half of springs at Nunn 7 NNE, CO see their last 32°F night by May 13; only one in ten is past it by May 2, and one in ten still has one after May 27. Planting tender crops after May 18 leaves a 30% risk of a frost on them, after May 21 20%, and after May 27 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 September 27 in half of years, as early as September 14 one year in ten, and holds off past October 9 one year in ten. A hard freeze of 28°F follows 10 days later, around October 7; in spring the one-in-ten date for 28°F is May 16, 11 days before the 32°F one. The freeze-free season lasts 136 days in a typical year, shorter than at 55% of the 110 Colorado stations; it reaches 153 days one year in ten and falls short of 118 one year in ten. On average 183 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 25, and return around September 19. Severe cold of 16°F or below comes every winter, usually between November 2 and April 2.

July is the warmest month at Nunn 7 NNE, CO, averaging 87°F by day and 54°F at night; December is the coldest at 41°F and 14°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 2,280 growing degree days a year (base 50°F), fewer than at 55% of the 110 Colorado stations. 29% of them (650) have built up by the end of June, and July adds the most, 636. Precipitation totals 13.4 inches a year, most in May (2.5") and least in January (0.3"); May to September bring 63% of it.

The nearest other station, Greeley Unc, CO, 15 miles south of Ault and 675 feet lower, has a last frost 11 days earlier (May 2), a first frost 11 days later (October 8), a season 23 days longer.

The first measurable snow (0.1 inch or more) in Ault usually arrives around November 3, and the last of the season around April 18. Those are the middle dates across the winters of 1991–2020 at Greeley 3.9 ENE, CO, 11.6 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 25 days after the last snow.

ZIP 80610 is 14 miles from Nunn 7 NNE, CO, which stands at 5,390 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80610 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.