December in San Francisco is cool and the wettest month of the year: the downtown station averages a high of 57.9°F (14.4°C), a low of 47.0°F (8.3°C) and 4.76 inches of rain. Rain falls on about 12 days, so most December days stay dry. Snow is essentially unheard of.
December is a month of storms, not a month of rain. Measurable rain fell on only 27% of Christmas Days from 1991 to 2020, yet the city's second-wettest day on record was New Year's Eve 2022, when 5.46 inches fell. Plan for a few big storms and a lot of crisp, clear days in between.
What Is December Weather Like in San Francisco?
December weather in San Francisco means short, cool days with highs in the upper 50s, and rain that arrives in a handful of storms. About 6 of every 10 December days are dry. Between storms, the air is often clean and sharp, with some of the clearest views of the year.
| Average high / low | 57.9°F (14.4°C) / 47.0°F (8.3°C) |
|---|---|
| Average rain | 4.76 in (121 mm), the wettest month of the year |
| Days with rain | About 12 with 0.01 in or more; about 8 with 0.10 in or more |
| Chance of rain on Christmas Day | 27% (1991-2020) |
| Chance of rain on New Year's Eve | 27% (1991-2020) |
| Daylight on December 21 | 9 hours 33 minutes; sunset about 4:54 PM |
| Ocean temperature | About 54°F offshore |
San Francisco Downtown station (USW00023272), NOAA 1991-2020 normals and daily records via RCC-ACIS. Ocean temperature from NOAA buoy 46026.
How Do Atmospheric Rivers Bring December's Biggest Storms?
December brings more big storm days than any other month, and most of them come from atmospheric rivers. From 1991 to 2020, downtown San Francisco averaged 1.27 December days a year with an inch of rain or more, and 8 of the city's 22 two-inch days in that span fell in December.
An atmospheric river is a long plume of moisture that flows off the Pacific, sometimes all the way from near Hawaii, when it is called a Pineapple Express. These storms are mild and windy, and they can drop several inches in a day. On December 31, 2022, one dumped 5.46 inches on downtown San Francisco, the city's second-wettest day on record.
A big storm day flips plans quickly. Expect flooded intersections, slow transit, flight delays at SFO and falling trees when wind and soaked soil combine. Most December storms pass in a day or two, so a flexible plan usually beats a canceled one.
What Is Christmas Weather Like in San Francisco?
Christmas in San Francisco is usually cool and dry: Christmas Day averages a high of 56.8°F and a low of 44.9°F, and measurable rain fell on 27% of Christmas Days from 1991 to 2020. The warmest Christmas reached 67°F in 1967, the coldest morning dropped to 35°F in 1990, and the wettest brought 1.15 inches in 2012.
Christmas Eve 2026 also brings the highest tide of the season. NOAA predicts a 7.23-foot king tide at the San Francisco gauge at 10:37 AM on December 24, enough to push water onto low parts of the Embarcadero on a calm day. King tides also arrive December 22, 23 and 25.
What Is New Year's Eve Weather Like in San Francisco?
New Year's Eve in San Francisco is usually dry and chilly at midnight: measurable rain fell on 27% of December 31sts from 1991 to 2020, and the average low is 46.9°F. Fireworks crowds along the Embarcadero stand in the upper 40s, often with a breeze off the bay.
The 2022 storm shows the exception: an all-day atmospheric river that soaked the city before the countdown. For viewing spots and wind, see the New Year's Eve fireworks weather guide.
What Is Tule Fog, and Will It Affect Holiday Drives?
Tule fog is thick ground fog that fills the Central Valley on calm, cold nights after rain. It rarely reaches San Francisco, but it can cut visibility to almost nothing on I-5, Highway 99 and I-80 toward Sacramento and Tahoe during holiday travel.
| Airport | December | January |
|---|---|---|
| Stockton | 7.2 | 8.6 |
| Sacramento Executive | 6.7 | 7.0 |
| Oakland | 1.9 | 1.6 |
Days with a minimum visibility of a quarter mile or less, July 2005 to June 2025, from airport weather reports in the Iowa Environmental Mesonet ASOS archive.
Stockton averages about 7 dense-fog days in December and Sacramento about 7, compared with fewer than 2 at Oakland. The fog usually thins by mid-morning, so a later start makes the drive safer. Read more about Central Valley fog and driving in fog, and check Caltrans QuickMap before you leave.
How Cold Do December Nights Get?
December nights in San Francisco are cool but rarely freezing: lows average 47.0°F downtown, and only about 1.4 nights a month drop to 40°F or colder. Cold snaps do happen. During the December 1990 freeze, downtown fell to 28°F on December 22, and the city's all-time low of 27°F came on December 11, 1932.
Calm, cold, clear nights trap wood smoke near the ground, which is when Winter Spare the Air alerts make burning wood illegal. Check the Spare the Air rules before lighting a fire, and see the coldest temperatures on record for how much colder the inland valleys get.
Is December a Good Time to Visit San Francisco?
December is a good time to visit San Francisco if you plan around storms. Dry days outnumber wet ones, crowds are smaller than in summer, and the hills turn green after the first rains. Days are the shortest of the year, with sunset around 4:51 PM in early December.
El Niño is this winter's extra wild card. In the strong El Niño winters of 1982 and 1997, December actually ran drier than normal, with the heavy rain arriving in January and February. Read the latest in the El Niño guide, and pack a hooded rain jacket and warm layers either way.
For a trip in the next week, check the San Francisco forecast for storm timing and rain totals, and the National Weather Service Bay Area office for flood or wind advisories. For dates further out, use the odds above and keep an indoor backup for about one day in three.