Frost Dates for 84535 — Monticello, Utah

Half of springs at Monticello 2E, UT see their last 32°F night by May 19; only one in ten is past it by May 3, and one in ten still has one after June 6. Planting tender crops after May 27 leaves a 30% risk of a frost on them, after May 31 20%, and after June 6 10%. The 18 days between the even-odds date and the one-in-ten date is narrower than at 47% of the 66 Utah stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 2 in half of years, as early as September 20 one year in ten, and holds off past October 15 one year in ten. A hard freeze of 28°F follows 10 days later, around October 12; in spring the one-in-ten date for 28°F is May 23, 14 days before the 32°F one. The freeze-free season lasts 133 days in a typical year, shorter than at 65% of the 66 Utah stations; it reaches 154 days one year in ten and falls short of 113 one year in ten. On average 180 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 June 1, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 13 and March 16.

July is the warmest month at Monticello 2E, UT, averaging 85°F by day and 54°F at night; January is the coldest at 36°F and 15°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 18% of years.

Warmth for growing adds up to 2,116 growing degree days a year (base 50°F), fewer than at 77% of the 66 Utah stations. 29% of them (614) have built up by the end of June, and July adds the most, 603. Precipitation totals 15.2 inches a year, most in August (1.8") and least in June (0.5"); May to September bring 41% of it.

The nearest other station, Blanding, UT, 21 miles southwest of Monticello and 788 feet lower, has a last frost 21 days earlier (April 28), a first frost 19 days later (October 21), a season 41 days longer.

The first measurable snow (0.1 inch or more) in Monticello usually arrives around October 30, and the last of the season around April 20. Those are the middle dates across the winters of 1991–2020 at Monticello 2E, UT, 0.9 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 29 days after the last snow.

ZIP 84535 is under a mile from Monticello 2E, UT, which stands at 6,820 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84535 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.