Frost Dates for 85622 — Green Valley, Arizona

Half of springs at Green Valley, AZ see their last 32°F night by February 25; only one in ten is past it by January 31, and one in ten still has one after March 18. Planting tender crops after March 4 leaves a 30% risk of a frost on them, after March 9 20%, and after March 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 November 27 in half of years, as early as November 12 one year in ten, and holds off past December 13 one year in ten. A hard freeze of 28°F follows 13 days later, around December 10; in spring the one-in-ten date for 28°F is February 27, 19 days before the 32°F one. The freeze-free season lasts 276 days in a typical year, longer than at 62% of the 98 Arizona stations; it reaches 305 days one year in ten and falls short of 248 one year in ten. On average 24 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 March 15, and return around November 16. Nights of 24°F, cold enough to damage hardier plants, come in 67% of winters and 16°F in 0%.

July is the warmest month at Green Valley, AZ, averaging 99°F by day and 72°F at night; December is the coldest at 66°F and 36°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 81% of years and March still brings one in 38% of years.

Warmth for growing adds up to 6,939 growing degree days a year (base 50°F), more than at 59% of the 102 Arizona stations. 41% of them (2,832) have built up by the end of June, and July adds the most, 1,099. Precipitation totals 12.9 inches a year, most in July (2.9") and least in May (0.2"); May to September bring 61% of it.

The nearest other station, Tucson International Airport, AZ, 19 miles north of Green Valley and 351 feet lower, has a last frost 20 days earlier (February 5), a first frost 12 days later (December 9), a season 31 days longer.

Measurable snow is rare here: only 2 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Green Valley, AZ, 4.7 miles away, so there is no typical first-snow date to plan around.

ZIP 85622 is 5 miles from Green Valley, AZ, which stands at 2,900 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 85629 (Sahuarita). The 2023 USDA Plant Hardiness Zone Map lists ZIP 85622 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.