Frost Dates for 85128 — Coolidge, Arizona

Half of springs at Casa Grande Nm, AZ see their last 32°F night by February 17; only one in ten is past it by January 22, and one in ten still has one after March 8. Planting tender crops after February 28 leaves a 30% risk of a frost on them, after March 3 20%, and after March 8 10%. The 19 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 98 Arizona stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 29 in half of years, as early as November 12 one year in ten, and holds off past December 15 one year in ten. A hard freeze of 28°F follows 13 days later, around December 12; in spring the one-in-ten date for 28°F is February 23, 13 days before the 32°F one. The freeze-free season lasts 284 days in a typical year, longer than at 66% of the 98 Arizona stations; it reaches 314 days one year in ten and falls short of 257 one year in ten. On average 29 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 19 days longer, to about March 8, and return around November 19. Nights of 24°F, cold enough to damage hardier plants, come in 57% of winters and 16°F in 3%.

July is the warmest month at Casa Grande Nm, AZ, averaging 107°F by day and 77°F at night; December is the coldest at 67°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 73% of years and March still brings one in 25% of years.

Warmth for growing adds up to 7,927 growing degree days a year (base 50°F), more than at 75% of the 102 Arizona stations. 40% of them (3,150) have built up by the end of June, and July adds the most, 1,297. Precipitation totals 8.3 inches a year, most in August (1.2") and least in June (0.1"); May to September bring 40% of it.

The nearest other station, Florence, AZ, 7 miles northeast of Coolidge, has a last frost 18 days earlier (January 30), a first frost 13 days later (December 12), a season 35 days longer.

Measurable snow is rare here: only 0 of 23 winters from 1991 to 2020 recorded 0.1 inch or more at Casa Grande Nm, AZ, 3.2 miles away, so there is no typical first-snow date to plan around.

ZIP 85128 is 3 miles from Casa Grande Nm, AZ, which stands at 1,419 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85128 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.