Frost Dates for 82935 — Green River, Wyoming

Half of springs at Green Rvr, WY see their last 32°F night by May 24; only one in ten is past it by May 7, and one in ten still has one after June 10. Planting tender crops after May 31 leaves a 30% risk of a frost on them, after June 4 20%, and after June 10 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 73% of the 33 Wyoming stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 22 in half of years, as early as September 7 one year in ten, and holds off past October 6 one year in ten. A hard freeze of 28°F follows 11 days later, around October 3; in spring the one-in-ten date for 28°F is May 28, 13 days before the 32°F one. The freeze-free season lasts 120 days in a typical year, shorter than at 64% of the 33 Wyoming stations; it reaches 143 days one year in ten and falls short of 99 one year in ten. On average 200 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 14 days longer, to about June 7, and return around September 13. Severe cold of 16°F or below comes every winter, usually between November 2 and March 27.

July is the warmest month at Green Rvr, WY, averaging 87°F by day and 53°F at night; January is the coldest at 31°F and 8°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 30% of years.

Warmth for growing adds up to 1,997 growing degree days a year (base 50°F), fewer than at 61% of the 33 Wyoming stations. 26% of them (515) have built up by the end of June, and July adds the most, 612. Precipitation totals 10.2 inches a year, most in May (1.7") and least in February (0.5"); May to September bring 45% of it.

The nearest other station, Rock Springs Fire Dept, WY, 21 miles east of Green River, has the same 50% last-frost date, a first frost 2 days later (September 24), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Green River usually arrives around November 2, and the last of the season around April 18. Those are the middle dates across the winters of 1991–2020 at Green Rvr, WY, 13.2 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 36 days after the last snow.

ZIP 82935 is 13 miles from Green Rvr, WY, which stands at 6,160 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 82935 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.