Frost Dates for 84004 — Alpine, Utah

Half of springs at Alpine, UT see their last 32°F night by May 3; only one in ten is past it by April 18, and one in ten still has one after May 26. Planting tender crops after May 12 leaves a 30% risk of a frost on them, after May 17 20%, and after May 26 10%. The 23 days between the even-odds date and the one-in-ten date is wider than at 86% 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 12 in half of years, as early as September 29 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 12 days later, around October 24; in spring the one-in-ten date for 28°F is May 5, 21 days before the 32°F one. The freeze-free season lasts 159 days in a typical year, longer than at 53% of the 66 Utah stations; it reaches 183 days one year in ten and falls short of 137 one year in ten. On average 133 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 20, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 26 and February 23.

July is the warmest month at Alpine, UT, averaging 90°F by day and 59°F at night; January is the coldest at 39°F and 22°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 57% of years.

Warmth for growing adds up to 2,867 growing degree days a year (base 50°F), more than at 52% of the 66 Utah stations. 30% of them (859) have built up by the end of June, and July adds the most, 744. Precipitation totals 21.0 inches a year, most in January (2.5") and least in July (0.6"); May to September bring 30% of it.

The nearest other station, Pleasant Grove, UT, 7 miles south of Alpine and 408 feet lower, has a last frost 16 days earlier (April 17), a first frost 13 days later (October 25), a season 29 days longer.

The first measurable snow (0.1 inch or more) in Alpine usually arrives around November 5, and the last of the season around April 19. Those are the middle dates across the winters of 1991–2020 at Alpine, UT, 0.4 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 14 days after the last snow.

ZIP 84004 is under a mile from Alpine, UT, which stands at 5,100 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84004 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.