Frost Dates for 82716 — Gillette, Wyoming

Half of springs at Gillette Campbell Airport, WY see their last 32°F night by May 22; only one in ten is past it by May 8, and one in ten still has one after June 4. Planting tender crops after May 28 leaves a 30% risk of a frost on them, after May 31 20%, and after June 4 10%. The 13 days between the even-odds date and the one-in-ten date is the narrowest of the 33 Wyoming stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 25 in half of years, as early as September 9 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 9 days later, around October 4; in spring the one-in-ten date for 28°F is May 22, 13 days before the 32°F one. The freeze-free season lasts 125 days in a typical year, longer than at 55% of the 33 Wyoming stations; it reaches 146 days one year in ten and falls short of 106 one year in ten. On average 179 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 June 3, and return around September 15. Severe cold of 16°F or below comes every winter, usually between October 31 and April 6.

July is the warmest month at Gillette Campbell Airport, WY, averaging 87°F by day and 56°F at night; January is the coldest at 36°F and 14°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 18% of years.

Warmth for growing adds up to 2,232 growing degree days a year (base 50°F), more than at 73% of the 33 Wyoming stations. 26% of them (570) have built up by the end of June, and July adds the most, 662. Precipitation totals 13.5 inches a year, most in May (2.6") and least in January (0.3"); May to September bring 60% of it.

The first measurable snow (0.1 inch or more) in Gillette usually arrives around October 10, and the last of the season around April 28. Those are the middle dates across the winters of 1991–2020 at Gillette 4SE, WY, 7.3 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 24 days after the last snow.

ZIP 82716 is 1 mile from Gillette Campbell Airport, WY, which stands at 4,354 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 82716 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.