Frost Dates for 82001 — Cheyenne, Wyoming

Half of springs at Cheyenne WFO, WY see their last 32°F night by May 14; only one in ten is past it by May 3, and one in ten still has one after May 28. Planting tender crops after May 20 leaves a 30% risk of a frost on them, after May 23 20%, and after May 28 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 58% of the 33 Wyoming stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 1 in half of years, as early as September 17 one year in ten, and holds off past October 14 one year in ten. A hard freeze of 28°F follows 9 days later, around October 10; in spring the one-in-ten date for 28°F is May 17, 11 days before the 32°F one. The freeze-free season lasts 139 days in a typical year, longer than at 79% of the 33 Wyoming stations; it reaches 155 days one year in ten and falls short of 119 one year in ten. On average 169 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 26, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 4 and March 31.

July is the warmest month at Cheyenne WFO, WY, averaging 83°F by day and 56°F at night; December is the coldest at 40°F and 18°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 2,065 growing degree days a year (base 50°F), fewer than at 55% of the 33 Wyoming stations. 27% of them (564) have built up by the end of June, and July adds the most, 598. Precipitation totals 16.0 inches a year, most in May (2.5") and least in January (0.4"); May to September bring 63% of it.

The nearest other station, Cheyenne, WY, under a mile north of Cheyenne, has a last frost 2 days earlier (May 12), the same first-frost date, a season 2 days longer.

The first measurable snow (0.1 inch or more) in Cheyenne usually arrives around October 9, and the last of the season around May 12. Those are the middle dates across the winters of 1991–2020 at Cheyenne WFO, WY, 0.7 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 2 days after the last snow.

ZIP 82001 is under a mile from Cheyenne WFO, WY, which stands at 6,119 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 82001 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.