Gas prices in the Bay Area and across the state continued to fall in December, with every metro area in Northern California registering a decrease at the pump since last month, an American Automobile Association spokeswoman said.

According to the AAA, California's average price for a gallon of regular unleaded gasoline was $3.62, down 23 cents since mid-November.

The average Bay Area price was $3.71, down 27 cents over the same time period, according to the AAA.

"Prices at the pump have steadily declined across the country as demand continues to be low and supplies remain robust," AAA Northern California spokeswoman Cynthia Harris said.

"The exception is the East Coast where supplies are increasing but remain somewhat tight following the disruption in distribution from Hurricane Sandy," Harris said.

Overall demand was expected to remain low into 2013, she said.

The highest-priced gas in the Bay Area was in San Francisco, where motorists paid an average $3.83 per gallon, according to the AAA.

The lowest was in Vallejo, where a gallon averaged $3.49.

— Bay City News Service

Are you receiving Express, our free daily e-mail edition? See a sample and sign-up for Express.