Frost Dates for 93516 — Boron, California

Half of springs at Randsburg, CA see their last 32°F night by March 19; only one in ten is past it by February 20, and one in ten still has one after April 13. Planting tender crops after March 31 leaves a 30% risk of a frost on them, after April 5 20%, and after April 13 10%. The 25 days between the even-odds date and the one-in-ten date is narrower than at 70% 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 25 in half of years, as early as November 5 one year in ten, and holds off past December 13 one year in ten. A hard freeze of 28°F follows 13 days later, around December 8; in spring the one-in-ten date for 28°F is March 29, 15 days before the 32°F one. The freeze-free season lasts 251 days in a typical year, shorter than at 67% of the 219 California stations; it reaches 285 days one year in ten and falls short of 219 one year in ten. On average 33 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 21 days longer, to about April 9, and return around November 12. Nights of 24°F, cold enough to damage hardier plants, come in 81% of winters and 16°F in 6%.

July is the warmest month at Randsburg, CA, averaging 101°F by day and 69°F at night; December is the coldest at 57°F and 35°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From May to October the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 71% of years and April still brings one in 28% of years.

Warmth for growing adds up to 5,700 growing degree days a year (base 50°F), more than at 84% of the 283 California stations. 36% of them (2,063) have built up by the end of June, and July adds the most, 1,076. Precipitation totals 6.8 inches a year, most in February (1.6") and least in June (0.0"); May to September bring 10% of it.

The nearest other station, Mojave, CA, 28 miles west of Boron and 835 feet lower, has a last frost 4 days earlier (March 15), a first frost 8 days earlier (November 17), a season 10 days shorter.

Measurable snow is rare here: only 5 of 18 winters from 1991 to 2020 recorded 0.1 inch or more at Mojave, CA, 27.7 miles away, so there is no typical first-snow date to plan around.

ZIP 93516 is 23 miles from Randsburg, CA, which stands at 3,570 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 93516 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°C) over 1991–2020; a zone describes winter lows, not frost dates.