Frost Dates for 94061 — Redwood City, California

In the 88% of winters that bring a 32°F night, half of springs at Redwood City, CA see their last 32°F night by January 17; only one in ten is past it by December 20, and one in ten still has one after February 16. Counting the winters with no freeze at all, the risk of a 32°F night after February 16 is under 9% and after January 17 44%. The 30 days between the even-odds date and the one-in-ten date is narrower than at 48% 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 12 in half of years, as early as November 24 one year in ten, and holds off past January 14 one year in ten. A hard freeze of 28°F is less common: it came in 38% of winters. The freeze-free season lasts 333 days in a typical year, longer than at 84% of the 219 California stations; it reaches 365 days one year in ten and falls short of 298 one year in ten. On average 6 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 39 days longer, to about February 25, and return around November 25. A 24°F night is unusual: 4% of winters had one.

July is the warmest month at Redwood City, CA, averaging 81°F by day and 57°F at night; December is the coldest at 59°F and 40°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 3,606 growing degree days a year (base 50°F), fewer than at 70% of the 283 California stations. 38% of them (1,375) have built up by the end of June, and July adds the most, 583. Precipitation totals 19.2 inches a year, most in December (3.9") and least in July (0.0"); May to September bring 4% of it.

The nearest other station, Woodside Fire Stn 1, CA, 3 miles southwest of Redwood City and 349 feet higher, has a last frost 39 days later (February 25), a first frost 17 days earlier (November 25), a season 59 days shorter.

Measurable snow is rare here: only 1 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Redwood City, CA, 0.9 miles away, so there is no typical first-snow date to plan around.

ZIP 94061 is under a mile from Redwood City, CA, which stands at 31 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station; its figures are presented in full for 94403 (San Mateo). The 2023 USDA Plant Hardiness Zone Map lists ZIP 94061 in zone 10a, the band where the coldest night of the year averaged 30 to 35°F (-1.1 to 1.7°C) over 1991–2020; a zone describes winter lows, not frost dates.