Frost Dates for 84040 — Layton, Utah

Half of springs at Weber Basin Pump Plt 3, UT see their last 32°F night by April 29; only one in ten is past it by April 6, and one in ten still has one after May 25. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 13 20%, and after May 25 10%. The 26 days between the even-odds date and the one-in-ten date is wider than at 95% 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 20 in half of years, as early as October 1 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 13 days later, around November 2; in spring the one-in-ten date for 28°F is May 5, 20 days before the 32°F one. The freeze-free season lasts 172 days in a typical year, longer than at 64% of the 66 Utah stations; it reaches 200 days one year in ten and falls short of 140 one year in ten. On average 132 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 16 days longer, to about May 15, and return around October 7. Severe cold of 16°F or below comes every winter, usually between November 28 and February 18.

July is the warmest month at Weber Basin Pump Plt 3, UT, averaging 92°F by day and 64°F at night; December is the coldest at 36°F and 20°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 40% of years.

Warmth for growing adds up to 3,017 growing degree days a year (base 50°F), more than at 61% of the 66 Utah stations. 27% of them (818) have built up by the end of June, and July adds the most, 861. Precipitation totals 26.0 inches a year, most in April (3.1") and least in July (0.8"); May to September bring 32% of it.

The nearest other station, Farmington 3 NW, UT, 5 miles south of Layton and 520 feet lower, has a last frost 10 days earlier (April 19), a first frost 1 day earlier (October 19), a season 9 days longer.

The first measurable snow (0.1 inch or more) in Layton usually arrives around November 26, and the last of the season around April 9. Those are the middle dates across the winters of 1991–2020 at Farmington 3 NW, UT, 4.6 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 20 days after the last snow.

ZIP 84040 is 2 miles from Weber Basin Pump Plt 3, UT, which stands at 4,900 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 84041 (Layton). The 2023 USDA Plant Hardiness Zone Map lists ZIP 84040 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.