The median price of an existing Orange County home slipped below the $500,000 mark in August, while sales here also saw a second straight month of declines, the California Association of Realtors said Wednesday.

The median price for an existing stand-alone OC home sold in August was $499,580, a $14,600 or 2.8% decrease from July and about the same price homes here were selling at a year earlier.

The area’s median sales price now is up 18% from the recent bottom of the market, seen in January 2009, according to the association’s figures.

Prices here are still off more than 33% from the peak of the market, when the median sales price for an OC home topped $747,000 in April 2007.

The number of sales here in August fell by 7.3% from a month earlier, the Realtor association said.

Sales were down 11.2% from a year earlier.

The median sales price of an existing home in California was $318,660 in August, about a 1% increase from July and an 8.6% increase from a year ago, according to the association.

Sales in California inched up about 2% from July’s levels, but were off nearly 15% from a year earlier.

The association excludes condominiums from its figures.

Including condos, the median price of an OC home sold in August was $440,000, a jump of more than $12,000 or 3% from a year earlier, according to a report from San Diego-based MDA DataQuick, a unit of Canada’s MacDonald, Dettwiler and Associates.

July was the first month that buyers across the country could not qualify for a tax credit of up to $8,000, which has hurt sales volumes both locally and nationally, especially among first-time buyers.