A cold weather system is expected to bring moderate rainfall to the Bay Area, several inches of snow in the Sierra, strong winds and lower temperatures ahead of a rainy Christmas.

The cold front, which was moving eastward over the Pacific Ocean, was expected to bring showers to the Bay Area on Saturday night through Sunday morning, said David King, a meteorologist with the National Weather Service’s Bay Area office.

San Francisco and other Bay Area cities may see between half an inch to an inch of rain, while the heaviest rainfall, up to 2 inches or more, is expected in the North Bay, he said.

Concord and other inland cities will probably see around a quarter of an inch to a half an inch, King said.

Ahead of the rainstorm, 118 flights were delayed and seven were canceled at San Francisco International Airport shortly before noon Saturday. Those figures are not “unusually high or low,” said Dennis Zamaria, an SFO airport duty manager, but airport officials expected additional cancellations and delays with worsening weather.

Gusty southern winds prompted the weather service to issue an advisory overnight Saturday until 7 a.m. Sunday for the East Bay hills, Diablo Range, Santa Lucia Mountains, Los Padres National Forest, mountains of San Benito County and interior Monterey County.

Winds of 25 to 35 mph were possible, with gusts up to 50 mph, weather officials said.

The cold front is expected to cause delays Sunday for travelers to the Sierra, where 6 to 12 inches of snow was forecast above 4,500 feet, King said. The heaviest snowfall is expected around midmorning Sunday through Sunday evening.

By Friday, more than 10 feet of snow had fallen at all Sierra resorts, said Joanna McWilliams, a spokeswoman for Heavenly and Kirkwood near the south end of Lake Tahoe, and Northstar, near the north end.

“If you’re traveling into the Sierra, allow yourself extra time, have extra clothes and food in your car, and make sure your car is gassed up,” King said.

San Francisco may see temperatures in the low 40s, and the North Bay Area could drop into 30-degree temperatures, with lower temperatures possible through Tuesday morning, King said.

Bay Area residents can expect a brief respite Sunday night through Tuesday, but King said the rain will probably return late Christmas Eve.

It’s too early to forecast how much rain will fall on Christmas, King said, but “Santa’s sleigh” will be riding into the Bay Area on a rainy weather system.

Lauren Hernández is a San Francisco Chronicle staff writer. Email: lauren.hernandez@sfchronicle.com Twitter: @LaurenPorFavor