Frost Dates for 92539 — Anza, California

Half of springs at Idyllwild Fire Dept, CA see their last 32°F night by May 16; only one in ten is past it by April 23, and one in ten still has one after June 5. Planting tender crops after May 27 leaves a 30% risk of a frost on them, after May 31 20%, and after June 5 10%. The 20 days between the even-odds date and the one-in-ten date is narrower than at 88% of the 220 California stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 24 in half of years, as early as October 1 one year in ten, and holds off past November 11 one year in ten. A hard freeze of 28°F follows 17 days later, around November 10; in spring the one-in-ten date for 28°F is May 19, 17 days before the 32°F one. The freeze-free season lasts 160 days in a typical year, shorter than at 89% of the 219 California stations; it reaches 191 days one year in ten and falls short of 131 one year in ten. On average 107 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 1, and return around October 6. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 57%.

August is the warmest month at Idyllwild Fire Dept, CA, averaging 86°F by day and 55°F at night; December is the coldest at 54°F and 30°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From July to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 72% of years and June still brings one in 18% of years.

Warmth for growing adds up to 2,838 growing degree days a year (base 50°F), fewer than at 86% of the 283 California stations. 28% of them (789) have built up by the end of June, and August adds the most, 639. Precipitation totals 24.6 inches a year, most in February (5.4") and least in June (0.1"); May to September bring 11% of it.

The nearest other station, Palomar Mountain Obsy, CA, 15 miles southwest of Anza and 170 feet higher, has a last frost 17 days earlier (April 29), a first frost 25 days later (November 18), a season 41 days longer.

Measurable snow is rare here: only 1 of 15 winters from 1991 to 2020 recorded 0.1 inch or more at Anza, CA, 0.4 miles away, so there is no typical first-snow date to plan around.

ZIP 92539 is 14 miles from Idyllwild Fire Dept, CA, which stands at 5,380 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 92549 (Idyllwild). The 2023 USDA Plant Hardiness Zone Map lists ZIP 92539 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.