Frost Dates for 85623 — Oracle, Arizona

Half of springs at Oracle Sp, AZ see their last 32°F night by March 29; only one in ten is past it by March 6, and one in ten still has one after April 29. Planting tender crops after April 6 leaves a 30% risk of a frost on them, after April 15 20%, and after April 29 10%. The 31 days between the even-odds date and the one-in-ten date is wider than at 85% 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 November 13 in half of years, as early as October 26 one year in ten, and holds off past November 30 one year in ten. A hard freeze of 28°F follows 11 days later, around November 24; in spring the one-in-ten date for 28°F is April 6, 23 days before the 32°F one. The freeze-free season lasts 225 days in a typical year, shorter than at 54% of the 98 Arizona stations; it reaches 255 days one year in ten and falls short of 192 one year in ten. On average 59 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 18 days longer, to about April 16, and return around November 1. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 47%.

July is the warmest month at Oracle Sp, AZ, averaging 94°F by day and 69°F at night; January is the coldest at 60°F and 31°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 88% of years and April still brings one in 36% of years.

Warmth for growing adds up to 5,061 growing degree days a year (base 50°F), fewer than at 59% of the 102 Arizona stations. 37% of them (1,857) have built up by the end of June, and July adds the most, 970.

The nearest other station, San Manuel, AZ, 8 miles east of Oracle and 1,175 feet lower, has a last frost 53 days earlier (February 4), a first frost 25 days later (December 8), a season 81 days longer.

The first measurable snow (0.1 inch or more) in Oracle usually arrives around December 20, and the last of the season around February 28. Those are the middle dates across the winters of 1991–2020 at Oracle 2 SE, AZ, 2.7 miles away: half of years saw snow earlier, half later. Snow fell in 95% of those winters. The last 32°F night of spring typically comes 29 days after the last snow.

ZIP 85623 is 3 miles from Oracle Sp, AZ, which stands at 4,595 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85623 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.