Frost Dates for 80751 — Sterling, Colorado

Half of springs at Sterling, CO see their last 32°F night by April 30; only one in ten is past it by April 16, and one in ten still has one after May 12. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 8 20%, and after May 12 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 81% of the 110 Colorado stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 9 in half of years, as early as September 28 one year in ten, and holds off past October 20 one year in ten. A hard freeze of 28°F follows 9 days later, around October 18; in spring the one-in-ten date for 28°F is May 3, 9 days before the 32°F one. The freeze-free season lasts 161 days in a typical year, longer than at 85% of the 110 Colorado stations; it reaches 178 days one year in ten and falls short of 143 one year in ten. On average 164 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 11, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 12 and March 13.

July is the warmest month at Sterling, CO, averaging 91°F by day and 62°F at night; December is the coldest at 42°F and 16°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 48% of years.

Warmth for growing adds up to 3,250 growing degree days a year (base 50°F), more than at 85% of the 110 Colorado stations. 33% of them (1,070) have built up by the end of June, and July adds the most, 827. Precipitation totals 15.2 inches a year, most in July (2.7") and least in January (0.3"); May to September bring 67% of it.

The nearest other station, Akron 4 E, CO, 33 miles south of Sterling and 568 feet higher, has a last frost 8 days later (May 8), a first frost 3 days earlier (October 6), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Sterling usually arrives around November 16, and the last of the season around March 23. Those are the middle dates across the winters of 1991–2020 at Sterling, CO, 0.6 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 38 days after the last snow.

ZIP 80751 is under a mile from Sterling, CO, which stands at 3,974 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 80751 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.