Frost Dates for 92310 — Fort Irwin, California

Half of springs at Barstow Daggett Airport, CA see their last 32°F night by February 19; only one in ten is past it by January 23, and one in ten still has one after March 11. Planting tender crops after February 28 leaves a 30% risk of a frost on them, after March 4 20%, and after March 11 10%. The 20 days between the even-odds date and the one-in-ten date is narrower than at 88% of the 220 California stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 26 in half of years, as early as November 10 one year in ten, and holds off past December 11 one year in ten. A hard freeze of 28°F follows 13 days later, around December 9; in spring the one-in-ten date for 28°F is February 25, 14 days before the 32°F one. The freeze-free season lasts 279 days in a typical year, longer than at 50% of the 219 California stations; it reaches 309 days one year in ten and falls short of 252 one year in ten. On average 24 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 20 days longer, to about March 11, and return around November 16. Nights of 24°F, cold enough to damage hardier plants, come in 68% of winters and 16°F in 2%.

July is the warmest month at Barstow Daggett Airport, CA, averaging 105°F by day and 74°F at night; December is the coldest at 60°F and 35°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 75% of years and March still brings one in 26% of years.

Warmth for growing adds up to 6,868 growing degree days a year (base 50°F), more than at 96% of the 283 California stations. 39% of them (2,684) have built up by the end of June, and July adds the most, 1,228. Precipitation totals 3.8 inches a year, most in February (0.7") and least in June (0.0"); May to September bring 21% of it.

The nearest other station, Barstow, CA, 32 miles southwest of Fort Irwin and 303 feet higher, has a last frost 3 days later (February 22), a first frost 3 days earlier (November 23), a season 8 days shorter.

Measurable snow is rare here: only 1 of 21 winters from 1991 to 2020 recorded 0.1 inch or more at Barstow Daggett Airport, CA, 28.7 miles away, so there is no typical first-snow date to plan around.

ZIP 92310 is 29 miles from Barstow Daggett Airport, CA, which stands at 1,917 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. That is farther than 25 miles, so local frost can differ noticeably from these figures. 1 other ZIP code shares the station; its figures are presented in full for 92365 (Newberry Springs). The 2023 USDA Plant Hardiness Zone Map lists ZIP 92310 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.