Frost Dates for 84302 — Brigham City, Utah

Half of springs at Brigham City Waste Plt, UT see their last 32°F night by May 5; only one in ten is past it by April 20, and one in ten still has one after May 29. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 19 20%, and after May 29 10%. The 24 days between the even-odds date and the one-in-ten date is wider than at 92% 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 5 in half of years, as early as September 20 one year in ten, and holds off past October 19 one year in ten. A hard freeze of 28°F follows 12 days later, around October 17; in spring the one-in-ten date for 28°F is May 5, 24 days before the 32°F one. The freeze-free season lasts 150 days in a typical year, shorter than at 53% of the 66 Utah stations; it reaches 172 days one year in ten and falls short of 123 one year in ten. On average 149 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 18 days longer, to about May 23, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 23 and February 26.

July is the warmest month at Brigham City Waste Plt, UT, averaging 91°F by day and 58°F at night; January is the coldest at 36°F and 18°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 61% of years.

Warmth for growing adds up to 2,761 growing degree days a year (base 50°F), fewer than at 53% of the 66 Utah stations. 30% of them (821) have built up by the end of June, and July adds the most, 752. Precipitation totals 15.4 inches a year, most in May (2.0") and least in July (0.4"); May to September bring 35% of it.

The nearest other station, Logan 5 SW Exp Farm, UT, 14 miles northeast of Brigham City and 248 feet higher, has a last frost 7 days later (May 12), a first frost 7 days earlier (September 28), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Brigham City usually arrives around November 17, and the last of the season around March 31. Those are the middle dates across the winters of 1991–2020 at Brigham City Waste Plt, UT, 1.1 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 35 days after the last snow.

ZIP 84302 is 1 mile from Brigham City Waste Plt, UT, which stands at 4,240 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84302 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.