Frost Dates for 92881 — Corona, California

In the 58% of winters that bring a 32°F night, half of springs at Riverside Municipal Airport, CA see their last 32°F night by January 9; only one in ten is past it by December 16, and one in ten still has one after February 21. Counting the winters with no freeze at all, the risk of a 32°F night after February 21 is under 6% and after January 9 29%. The 43 days between the even-odds date and the one-in-ten date is wider than at 91% 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 December 30 in half of years, as early as December 5 one year in ten, and holds off past February 6 one year in ten. A hard freeze of 28°F is less common: it came in 7% of winters. The freeze-free season lasts 362 days in a typical year, longer than at 98% of the 219 California stations; it reaches 365 days one year in ten and falls short of 319 one year in ten. On average 4 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 35 days longer, to about February 13, and return around December 12. No night reached 24°F in 1991–2020.

August is the warmest month at Riverside Municipal Airport, CA, averaging 95°F by day and 65°F at night; December is the coldest at 67°F and 43°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 12% of years.

Warmth for growing adds up to 5,993 growing degree days a year (base 50°F), more than at 90% of the 283 California stations. 38% of them (2,300) have built up by the end of June, and August adds the most, 924. Precipitation totals 9.3 inches a year, most in February (2.4") and least in June (0.0"); May to September bring 4% of it.

The nearest other station, Chino Airport, CA, 11 miles northwest of Corona and 155 feet lower, has a last frost 8 days later (January 17), a first frost 11 days earlier (December 19), a season 27 days shorter.

Measurable snow is rare here: only 0 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Riverside Fire Stn 3, CA, 11.5 miles away, so there is no typical first-snow date to plan around.

ZIP 92881 is 10 miles from Riverside Municipal Airport, CA, which stands at 805 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 92503 (Riverside). The 2023 USDA Plant Hardiness Zone Map lists ZIP 92881 in zone 10a, the band where the coldest night of the year averaged 30 to 35°F (-1.1 to 1.7°C) over 1991–2020; a zone describes winter lows, not frost dates.