Frost Dates for 86305 — Prescott, Arizona

Half of springs at Chino Valley, AZ see their last 32°F night by April 27; only one in ten is past it by April 10, and one in ten still has one after May 18. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 10 20%, and after May 18 10%. The 21 days between the even-odds date and the one-in-ten date is narrower than at 47% of the 98 Arizona 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 24 in half of years, as early as October 9 one year in ten, and holds off past November 8 one year in ten. A hard freeze of 28°F follows 12 days later, around November 5; in spring the one-in-ten date for 28°F is April 29, 19 days before the 32°F one. The freeze-free season lasts 178 days in a typical year, shorter than at 77% of the 98 Arizona stations; it reaches 199 days one year in ten and falls short of 155 one year in ten. On average 127 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 May 13, and return around October 12. Severe cold of 16°F or below comes in 98% of winters, usually between December 12 and January 30.

July is the warmest month at Chino Valley, AZ, averaging 93°F by day and 62°F at night; December is the coldest at 53°F and 24°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 40% of years.

Warmth for growing adds up to 3,830 growing degree days a year (base 50°F), fewer than at 75% of the 102 Arizona stations. 34% of them (1,287) have built up by the end of June, and July adds the most, 865.

The nearest other station, Prescott Love Field, AZ, 13 miles east of Prescott and 292 feet higher, has a last frost 7 days earlier (April 20), a first frost 3 days later (October 27), a season 10 days longer.

The first measurable snow (0.1 inch or more) in Prescott usually arrives around December 20, and the last of the season around March 9. Those are the middle dates across the winters of 1991–2020 at Prescott, AZ, 14.7 miles away: half of years saw snow earlier, half later. Snow fell in 97% of those winters. The last 32°F night of spring typically comes 49 days after the last snow.

ZIP 86305 is 11 miles from Chino Valley, AZ, which stands at 4,750 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 86305 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.