The housing slump is hitting Southern California with a vengenance — sales volume plummeted 45.3 percent from year-ago levels in December, while median prices hit their lowest level since February 2005. According to a report released Tuesday by real estate analytics firm DataQuick, 13,240 new and resale houses and condos were sold in Los Angeles, Riverside, San Diego, Ventura, San Bernardino and Orange counties in December. The firm said the sales number was “by far the lowest for any December in DataQuick’s statistics, which go back to 1988” — if fact, DataQuick said that December 2007’s sale volume was more than 20 percent below the previous December low, recorded in 1990. “Today’s numbers form a lousy basis for trending and forecasting,” said Marshall Prentice, DataQuick’s president, in a press statement. “We’re in the midst of turbulence and we won’t know what really has been going on until things have settled down and we can look back.” Prices didn’t fare much better, either. The median price paid for a home in Southern California was $425,000 during December, the lowest since $420,000 in February 2005. Last month’s median was 15.8 percent below the $505,000 peak reached last spring and summer, DataQuick said. “While the steep decline in median sales price does reflect a drop in prices, it also reflects significant shifts in the types of homes selling,” the company said in its report. “Particularly noticeable is a drop-off in sales of more expensive homes financed with “jumbo” mortgages.” (Hat tip: Calculated Risk)