Frost Dates for 84648 — Nephi, Utah

Half of springs at Nephi, UT see their last 32°F night by May 6; only one in ten is past it by April 21, and one in ten still has one after May 24. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 18 20%, and after May 24 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 10 in half of years, as early as September 28 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 13 days later, around October 23; in spring the one-in-ten date for 28°F is May 9, 15 days before the 32°F one. The freeze-free season lasts 156 days in a typical year, longer than at 50% of the 66 Utah stations; it reaches 177 days one year in ten and falls short of 132 one year in ten. On average 148 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 20, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 22 and February 25.

July is the warmest month at Nephi, UT, averaging 90°F by day and 61°F at night; December is the coldest at 37°F and 20°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 64% of years.

Warmth for growing adds up to 2,928 growing degree days a year (base 50°F), more than at 55% of the 66 Utah stations. 29% of them (853) have built up by the end of June, and July adds the most, 787. Precipitation totals 13.7 inches a year, most in April (1.6") and least in July (0.6"); May to September bring 34% of it.

The nearest other station, Santaquin Chlorinator, UT, 19 miles north of Nephi, has a last frost 2 days earlier (May 4), a first frost 1 day later (October 11), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Nephi usually arrives around November 11, and the last of the season around April 8. Those are the middle dates across the winters of 1991–2020 at Nephi, UT, 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 28 days after the last snow.

ZIP 84648 is 3 miles from Nephi, UT, which stands at 5,146 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84648 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.