Home sales in the San Francisco Bay Area rose 22.9% in July from year-ago levels, with 8,461 homes sold.

That compares to 6,887 closings a year ago, real estate research firm DataQuick said Wednesday.

It's also the 13th consecutive year-over-year sales increase in the nine-county Bay Area, suggesting increased demand and a stabilizing housing market, according to DataQuick.

In July, the median price for new homes sales in the San Francisco Bay rose 1% from June, hitting $412,000. That's up 12.6% from a median sales price of $374,000 a year earlier.

The Bay Area's median price in July hit its highest level since August of 2008 as more buyers snapped up properties in the mid-level and move-up markets.

About 41.6% of July sales were in the $500,000 plus-price range.

Foreclosure resales and short sales made up 34.6% of all July sales down from 44.5% a year ago — an indicator that distressed inventory levels are starting to subside.

Despite an uptick in year-over-year sales and prices, DataQuick believes mortgage availability declined last month.   

"Adjustable-rate mortgages accounted for 13.3% of the Bay Area’s home purchase loans," DataQuick wrote. "That was down from a revised 14.2% in June, and down from 14.4% in July last year. Since 2000, ARMs have accounted for 49.6% of all purchase loans. ARMs hit a low of 3% of loans in January 2009."