Frost Dates for 84624 — Delta, Utah

Half of springs at Delta, UT see their last 32°F night by May 16; only one in ten is past it by April 29, and one in ten still has one after June 5. Planting tender crops after May 23 leaves a 30% risk of a frost on them, after May 28 20%, and after June 5 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 61% of the 66 Utah stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 29 in half of years, as early as September 16 one year in ten, and holds off past October 11 one year in ten. A hard freeze of 28°F follows 10 days later, around October 9; in spring the one-in-ten date for 28°F is May 19, 17 days before the 32°F one. The freeze-free season lasts 137 days in a typical year, shorter than at 64% of the 66 Utah stations; it reaches 155 days one year in ten and falls short of 113 one year in ten. On average 176 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 13 days longer, to about May 29, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 8 and March 12.

July is the warmest month at Delta, UT, averaging 95°F by day and 57°F at night; December is the coldest at 39°F and 15°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 86% of years and June still brings one in 14% of years.

Warmth for growing adds up to 3,015 growing degree days a year (base 50°F), more than at 58% of the 66 Utah stations. 30% of them (908) have built up by the end of June, and July adds the most, 813. Precipitation totals 7.9 inches a year, most in April (0.9") and least in July (0.4"); May to September bring 38% of it.

The nearest other station, Fillmore, UT, 29 miles southeast of Delta and 507 feet higher, has a last frost 12 days earlier (May 4), a first frost 15 days later (October 14), a season 23 days longer.

The first measurable snow (0.1 inch or more) in Delta usually arrives around November 25, and the last of the season around April 6. Those are the middle dates across the winters of 1991–2020 at Delta, UT, 2.4 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 40 days after the last snow.

ZIP 84624 is 2 miles from Delta, UT, which stands at 4,620 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84624 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.