Frost Dates for 92536 — Aguanga, California

Half of springs at Palomar Mountain Obsy, CA see their last 32°F night by April 29; only one in ten is past it by April 2, and one in ten still has one after May 29. Planting tender crops after May 10 leaves a 30% risk of a frost on them, after May 18 20%, and after May 29 10%. The 30 days between the even-odds date and the one-in-ten date is narrower than at 48% of the 220 California 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 18 in half of years, as early as October 27 one year in ten, and holds off past December 8 one year in ten. A hard freeze of 28°F follows 18 days later, around December 6; in spring the one-in-ten date for 28°F is May 5, 24 days before the 32°F one. The freeze-free season lasts 201 days in a typical year, shorter than at 80% of the 219 California stations; it reaches 236 days one year in ten and falls short of 164 one year in ten. On average 49 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 20 days longer, to about May 19, and return around November 1. Nights of 24°F, cold enough to damage hardier plants, come in 95% of winters and 16°F in 11%.

August is the warmest month at Palomar Mountain Obsy, CA, averaging 84°F by day and 65°F at night; February is the coldest at 51°F and 36°F. A freezing night is all but certain in every month from December to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 84% of years and May still brings one in 41% of years.

Warmth for growing adds up to 3,690 growing degree days a year (base 50°F), fewer than at 67% of the 283 California stations. 30% of them (1,124) have built up by the end of June, and August adds the most, 758. Precipitation totals 30.5 inches a year, most in February (7.3") and least in June (0.2"); May to September bring 9% of it.

The nearest other station, Hemet, CA, 18 miles north of Aguanga and 3,739 feet lower, has a last frost 109 days earlier (January 10), a first frost 35 days later (December 23), a season 149 days longer.

The first measurable snow (0.1 inch or more) in Aguanga usually arrives around December 10, and the last of the season around March 26. Those are the middle dates across the winters of 1991–2020 at Palomar Mountain Obsy, CA, 7.5 miles away: half of years saw snow earlier, half later. Snow fell in 92% of those winters. The last 32°F night of spring typically comes 34 days after the last snow.

ZIP 92536 is 8 miles from Palomar Mountain Obsy, CA, which stands at 5,550 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 92536 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°C) over 1991–2020; a zone describes winter lows, not frost dates.