Major cities in the Bay Area are experiencing record rainfall during the first half of December, the National Weather Service said Tuesday. “It's the wettest start ever for December,” said National Weather Service meteorologist Charles Bell. San Francisco has seen more than 9.14 inches of rain through early this morning. The previous record of 7.10 inches was set in 1889. Data go back as far as 1849, Bell said. The amount of rain in the first 15 days of December in Oakland is more than two and a half inches above the previous record set in 1950. San Jose has seen the wettest December since 1906. The amount of rain that has fallen in San Jose is more than two inches above the 1906 record.For the year, San Francisco has received 12.58 inches of rain through 3 a.m. this morning, Bell said. As of 4 p.m. Monday, that was 184 percent of the normal amount of rain the city receives each water year, which starts July 1 in California. Last year, San Francisco was at 31 percent of normal. “It's a substantial increase from a year ago,” Bell said. The amount of rain that has fallen in Oakland this year is 191 percent of normal and the amount of rain this year in San Jose is 244 percent of normal, according to data from the National Weather Service.