Frost Dates for 94514 — Byron, California

Half of springs at Tracy Pumping Plt, CA see their last 32°F night by January 19; only one in ten is past it by December 25, and one in ten still has one after February 17. Planting tender crops after January 31 leaves a 30% risk of a frost on them, after February 6 20%, and after February 17 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 December 10 in half of years, as early as November 26 one year in ten, and holds off past January 7 one year in ten. A hard freeze of 28°F follows 12 days later, around December 22; in spring the one-in-ten date for 28°F is January 22, 26 days before the 32°F one. The freeze-free season lasts 330 days in a typical year, longer than at 82% of the 219 California stations; it reaches 358 days one year in ten and falls short of 297 one year in ten. On average 10 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 February 21, and return around November 29. A 24°F night is unusual: 14% of winters had one.

July is the warmest month at Tracy Pumping Plt, CA, averaging 93°F by day and 62°F at night; January is the coldest at 56°F and 41°F. From March to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 24% of years.

Warmth for growing adds up to 5,166 growing degree days a year (base 50°F), more than at 69% of the 283 California stations. 38% of them (1,983) have built up by the end of June, and July adds the most, 856. Precipitation totals 12.3 inches a year, most in January (2.5") and least in July (0.0"); May to September bring 6% of it.

The nearest other station, Antioch Pumping Plt #3, CA, 12 miles northwest of Byron, has a last frost 7 days earlier (January 12), a first frost 9 days later (December 19), a season 13 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Tracy Pumping Plt, CA, 3.8 miles away, so there is no typical first-snow date to plan around.

ZIP 94514 is 4 miles from Tracy Pumping Plt, CA, which stands at 61 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 95391 (Mountain House). The 2023 USDA Plant Hardiness Zone Map lists ZIP 94514 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.