Frost Dates for 84066 — Roosevelt, Utah

Half of springs at Roosevelt Radio, UT see their last 32°F night by May 23; only one in ten is past it by May 9, and one in ten still has one after June 9. Planting tender crops after May 31 leaves a 30% risk of a frost on them, after June 3 20%, and after June 9 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 September 22 in half of years, as early as September 8 one year in ten, and holds off past October 3 one year in ten. A hard freeze of 28°F follows 10 days later, around October 2; in spring the one-in-ten date for 28°F is May 25, 15 days before the 32°F one. The freeze-free season lasts 121 days in a typical year, shorter than at 73% of the 66 Utah stations; it reaches 139 days one year in ten and falls short of 99 one year in ten. On average 190 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 June 8, and return around September 12. Severe cold of 16°F or below comes every winter, usually between November 2 and March 31.

July is the warmest month at Roosevelt Radio, UT, averaging 93°F by day and 52°F at night; January is the coldest at 31°F and 2°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 27% of years.

Warmth for growing adds up to 2,465 growing degree days a year (base 50°F), fewer than at 65% of the 66 Utah stations. 31% of them (753) have built up by the end of June, and July adds the most, 694. Precipitation totals 7.4 inches a year, most in September (1.0") and least in February (0.4"); May to September bring 46% of it.

The nearest other station, Duchesne, UT, 23 miles southwest of Roosevelt and 537 feet higher, has a last frost 17 days earlier (May 6), a first frost 13 days later (October 5), a season 29 days longer.

The first measurable snow (0.1 inch or more) in Roosevelt usually arrives around December 3, and the last of the season around February 25. Those are the middle dates across the winters of 1991–2020 at Roosevelt Radio, UT, 4.1 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 87 days after the last snow.

ZIP 84066 is 4 miles from Roosevelt Radio, UT, which stands at 5,014 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 84066 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.