Frost Dates for 84065 — Riverton, Utah

Half of springs at Draper-Point Of Mountain, UT see their last 32°F night by April 18; only one in ten is past it by March 31, and one in ten still has one after May 6. Planting tender crops after April 25 leaves a 30% risk of a frost on them, after April 30 20%, and after May 6 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 47% of the 66 Utah stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 7 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 11 days later, around November 2; in spring the one-in-ten date for 28°F is April 17, 19 days before the 32°F one. The freeze-free season lasts 185 days in a typical year, longer than at 85% of the 66 Utah stations; it reaches 209 days one year in ten and falls short of 162 one year in ten. On average 116 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 May 2, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 4 and February 10.

July is the warmest month at Draper-Point Of Mountain, UT, averaging 94°F by day and 66°F at night; January is the coldest at 40°F and 25°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 85% of years and May still brings one in 18% of years.

Warmth for growing adds up to 3,706 growing degree days a year (base 50°F), more than at 88% of the 66 Utah stations. 32% of them (1,178) have built up by the end of June, and July adds the most, 914.

The nearest other station, Alpine, UT, 10 miles east of Riverton and 594 feet higher, has a last frost 15 days later (May 3), a first frost 10 days earlier (October 12), a season 26 days shorter.

The first measurable snow (0.1 inch or more) in Riverton usually arrives around November 22, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Draper-Point Of Mountain, UT, 3.5 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 15 days after the last snow.

ZIP 84065 is 4 miles from Draper-Point Of Mountain, UT, which stands at 4,506 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 84096 (Herriman). The 2023 USDA Plant Hardiness Zone Map lists ZIP 84065 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.