Frost Dates for 84029 — Grantsville, Utah

Half of springs at Grantsville 2W, UT see their last 32°F night by May 2; only one in ten is past it by April 17, and one in ten still has one after May 19. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 13 20%, and after May 19 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 68% of the 66 Utah stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 14 in half of years, as early as September 30 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 11 days later, around October 25; in spring the one-in-ten date for 28°F is May 5, 14 days before the 32°F one. The freeze-free season lasts 164 days in a typical year, longer than at 59% of the 66 Utah stations; it reaches 183 days one year in ten and falls short of 141 one year in ten. On average 142 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 16, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 24 and February 26.

July is the warmest month at Grantsville 2W, UT, averaging 92°F by day and 64°F at night; January is the coldest at 37°F and 19°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 53% of years.

Warmth for growing adds up to 3,142 growing degree days a year (base 50°F), more than at 67% of the 66 Utah stations. 29% of them (899) have built up by the end of June, and July adds the most, 866. Precipitation totals 11.4 inches a year, most in April (1.5") and least in June (0.7"); May to September bring 39% of it.

The nearest other station, Tooele, UT, 21 miles southeast of Grantsville and 394 feet higher, has the same 50% last-frost date, a first frost 2 days later (October 16), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Grantsville usually arrives around November 19, and the last of the season around April 7. Those are the middle dates across the winters of 1991–2020 at Grantsville 2W, UT, 10.4 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 25 days after the last snow.

ZIP 84029 is 10 miles from Grantsville 2W, UT, which stands at 4,550 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84029 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.