Frost Dates for 84642 — Manti, Utah

Half of springs at Manti, UT see their last 32°F night by May 11; only one in ten is past it by April 25, and one in ten still has one after June 1. Planting tender crops after May 19 leaves a 30% risk of a frost on them, after May 25 20%, and after June 1 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 74% of the 66 Utah stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by October 6 in half of years, as early as September 24 one year in ten, and holds off past October 19 one year in ten. A hard freeze of 28°F follows 10 days later, around October 16; in spring the one-in-ten date for 28°F is May 14, 18 days before the 32°F one. The freeze-free season lasts 146 days in a typical year, shorter than at 58% of the 66 Utah stations; it reaches 167 days one year in ten and falls short of 122 one year in ten. On average 167 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 17 days longer, to about May 28, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 18 and March 1.

July is the warmest month at Manti, UT, averaging 87°F by day and 57°F at night; December is the coldest at 38°F and 19°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 75% of years and June still brings one in 10% of years.

Warmth for growing adds up to 2,504 growing degree days a year (base 50°F), fewer than at 64% of the 66 Utah stations. 28% of them (708) have built up by the end of June, and July adds the most, 685. Precipitation totals 13.2 inches a year, most in May (1.5") and least in July (0.7"); May to September bring 38% of it.

The nearest other station, Manti Radio Kmti, UT, 5 miles northwest of Manti and 242 feet lower, has a last frost 20 days later (May 31), a first frost 15 days earlier (September 21), a season 32 days shorter.

The first measurable snow (0.1 inch or more) in Manti usually arrives around November 4, and the last of the season around April 19. Those are the middle dates across the winters of 1991–2020 at Manti, 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 22 days after the last snow.

ZIP 84642 is 4 miles from Manti, UT, which stands at 5,740 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84642 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.