Frost Dates for 95926 — Chico, California

Half of springs at Chico Univ Farm, CA see their last 32°F night by March 4; only one in ten is past it by February 8, and one in ten still has one after April 2. Planting tender crops after March 15 leaves a 30% risk of a frost on them, after March 23 20%, and after April 2 10%. The 29 days between the even-odds date and the one-in-ten date is narrower than at 52% 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 17 in half of years, as early as November 1 one year in ten, and holds off past December 5 one year in ten. A hard freeze of 28°F follows 16 days later, around December 3; in spring the one-in-ten date for 28°F is March 1, 32 days before the 32°F one. The freeze-free season lasts 257 days in a typical year, shorter than at 64% of the 219 California stations; it reaches 290 days one year in ten and falls short of 223 one year in ten. On average 40 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 32 days longer, to about April 5, and return around November 4. Nights of 24°F, cold enough to damage hardier plants, come in 66% of winters and 16°F in 3%.

July is the warmest month at Chico Univ Farm, CA, averaging 95°F by day and 61°F at night; January is the coldest at 56°F and 36°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From May to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 88% of years and March still brings one in 51% of years and April still brings one in 12% of years.

Warmth for growing adds up to 4,667 growing degree days a year (base 50°F), more than at 53% of the 283 California stations. 37% of them (1,729) have built up by the end of June, and July adds the most, 871.

The nearest other station, Paradise, CA, 12 miles east of Chico and 1,565 feet higher, has a last frost 25 days earlier (February 7), a first frost 31 days later (December 18), a season 56 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Chico Univ Farm, CA, 4 miles away, so there is no typical first-snow date to plan around.

ZIP 95926 is 4 miles from Chico Univ Farm, CA, which stands at 185 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95926 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.