Frost Dates for 84701 — Richfield, Utah

Half of springs at Richfield Radio Ksvc, UT see their last 32°F night by May 21; only one in ten is past it by May 4, and one in ten still has one after June 7. Planting tender crops after May 29 leaves a 30% risk of a frost on them, after June 2 20%, and after June 7 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 68% of the 66 Utah stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 24 in half of years, as early as September 12 one year in ten, and holds off past October 6 one year in ten. A hard freeze of 28°F follows 10 days later, around October 4; in spring the one-in-ten date for 28°F is May 22, 16 days before the 32°F one. The freeze-free season lasts 125 days in a typical year, shorter than at 70% of the 66 Utah stations; it reaches 146 days one year in ten and falls short of 101 one year in ten. On average 176 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 15 days longer, to about June 5, and return around September 16. Severe cold of 16°F or below comes every winter, usually between November 6 and March 12.

July is the warmest month at Richfield Radio Ksvc, UT, averaging 90°F by day and 54°F at night; December is the coldest at 41°F and 16°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 24% of years.

Warmth for growing adds up to 2,528 growing degree days a year (base 50°F), fewer than at 61% of the 66 Utah stations. 30% of them (760) have built up by the end of June, and July adds the most, 684. Precipitation totals 8.0 inches a year, most in May (1.0") and least in June (0.4"); May to September bring 45% of it.

The nearest other station, Fillmore, UT, 19 miles northwest of Richfield and 158 feet lower, has a last frost 17 days earlier (May 4), a first frost 20 days later (October 14), a season 35 days longer.

The first measurable snow (0.1 inch or more) in Richfield usually arrives around November 19, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Richfield Radio Ksvc, UT, 0.4 miles away: half of years saw snow earlier, half later. Snow fell in 96% of those winters. The last 32°F night of spring typically comes 51 days after the last snow.

ZIP 84701 is under a mile from Richfield Radio Ksvc, UT, which stands at 5,285 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84701 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.