Frost Dates for 95959 — Nevada City, California

Half of springs at Nevada City, CA see their last 32°F night by April 14; only one in ten is past it by March 15, and one in ten still has one after May 7. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 29 20%, and after May 7 10%. The 23 days between the even-odds date and the one-in-ten date is narrower than at 78% 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 20 in half of years, as early as October 23 one year in ten, and holds off past December 12 one year in ten. A hard freeze of 28°F follows 18 days later, around December 8; in spring the one-in-ten date for 28°F is April 18, 19 days before the 32°F one. The freeze-free season lasts 218 days in a typical year, shorter than at 75% of the 219 California stations; it reaches 253 days one year in ten and falls short of 184 one year in ten. On average 49 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 16 days longer, to about April 30, and return around November 2. Nights of 24°F, cold enough to damage hardier plants, come in 70% of winters and 16°F in 4%.

July is the warmest month at Nevada City, CA, averaging 87°F by day and 60°F at night; December is the coldest at 48°F and 35°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 88% of years and April still brings one in 70% of years and May still brings one in 17% of years.

Warmth for growing adds up to 3,339 growing degree days a year (base 50°F), fewer than at 75% of the 283 California stations. 30% of them (987) have built up by the end of June, and July adds the most, 727. Precipitation totals 62.2 inches a year, most in December (12.2") and least in July (0.0"); May to September bring 7% of it.

The nearest other station, Grass Valley #2, CA, 9 miles southwest of Nevada City and 381 feet lower, has a last frost 4 days earlier (April 10), a first frost 7 days earlier (November 13), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Nevada City usually arrives around December 17, and the last of the season around March 23. Those are the middle dates across the winters of 1991–2020 at Nevada City, CA, 4.5 miles away: half of years saw snow earlier, half later. Snow fell in 97% of those winters. The last 32°F night of spring typically comes 22 days after the last snow.

ZIP 95959 is 5 miles from Nevada City, CA, which stands at 2,781 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 95959 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.