Frost Dates for 92220 — Banning, California

Half of springs at San Jacinto, CA see their last 32°F night by January 31; only one in ten is past it by December 31, and one in ten still has one after February 28. Planting tender crops after February 14 leaves a 30% risk of a frost on them, after February 21 20%, and after February 28 10%. The 28 days between the even-odds date and the one-in-ten date is narrower than at 60% 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 10 in half of years, as early as November 22 one year in ten, and holds off past January 6 one year in ten. A hard freeze of 28°F follows 11 days later, around December 21; in spring the one-in-ten date for 28°F is January 29, 30 days before the 32°F one. The freeze-free season lasts 315 days in a typical year, longer than at 72% of the 219 California stations; it reaches 348 days one year in ten and falls short of 274 one year in ten. On average 15 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 33 days longer, to about March 5, and return around November 24. A 24°F night is unusual: 11% of winters had one.

August is the warmest month at San Jacinto, CA, averaging 97°F by day and 64°F at night; December is the coldest at 65°F and 39°F. From March to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 42% of years.

Warmth for growing adds up to 5,606 growing degree days a year (base 50°F), more than at 83% of the 283 California stations. 37% of them (2,056) have built up by the end of June, and August adds the most, 942. Precipitation totals 12.4 inches a year, most in February (2.8") and least in June (0.1"); May to September bring 10% of it.

The nearest other station, Hemet, CA, 13 miles south of Banning and 286 feet higher, has a last frost 21 days earlier (January 10), a first frost 13 days later (December 23), a season 35 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at San Jacinto, CA, 10.2 miles away, so there is no typical first-snow date to plan around.

ZIP 92220 is 10 miles from San Jacinto, CA, which stands at 1,525 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 8 other ZIP codes share the station; its figures are presented in full for 92223 (Beaumont). The 2023 USDA Plant Hardiness Zone Map lists ZIP 92220 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.