More than 6,330 new and resale houses and condos in the Bay Area closed escrow last month, down 5.4 percent since August and down nearly 20 percent from September of 2009.
Overall, September home sales in the Bay Area were the lowest since 2007, according to DataQuick.
Napa was the only Bay Area county to see an increase in the number of home sales, 3.5 percent, while San Francisco saw a decline of 17.5 percent and Alameda had a 27.1 percent decrease.
Last month, the overall median amount paid for Bay Area houses and condos was $395,000, a decrease of 40.6 percent from June and July in 2007.
Home flipping–when a house is bought and then sold rapidly–has increased slightly since August in the Bay Area. In September, 2.4 percent of the homes purchased in the open market were bought and sold within six months, up from 2.2 percent in August.
The drop in home sales could continue until the economy rebounds, fostering job confidence and leading to spending increases, according to DataQuick.