The median price of an existing Orange County house is up 22.5% from last July.

The median price of an existing Orange County house soared to $675,000 in July, up 22.5 percent from last July, the California Association of Realtors reported.

The price was $551,160 in July 2012 and $661,740 in June of this year.

Home resales in the county increased 5.2 percent over a year ago, the association said.

Statewide, the median price for an existing, single-family detached home was $433,760, up 29.8 percent from $334,220 in July 2012.

California had a 1.5 percent year-over-year sales bump last month. It was the first annual increase in sales for a month since December 2012.

“The spike in interest rates in June prompted homebuyers to delay escrow closings in hopes that rates would fall back,” said Don Faught, the association’s president. “As buyers recognized rates had stabilized, they moved forward to close escrow, which lifted July’s sales from both the previous month and year.”

A limited supply of homes for sale drove price increases this year, especially in coastal areas, said Leslie Appleton-Young, the association’s vice president and chief economist.

Appleton-Young said prices should continue to grow but at a slower pace.

“Inventory levels are starting to build in some areas as price gains free up previously underwater homes and encourage homeowners reluctant to list because of the scarcity of homes to purchase,” she said.

The $675,000 Orange County median is still far below the resale high of $775,420 reported by the association in June 2007.

DataQuick Information Systems – which measures all home sales, including new houses and condos – reported this week that the median price for an Orange County home was $539,500, up 19.9 percent from July 2012. It said all sales rose 42.6 percent over last July.

Also this week, real estate website Trulia called Orange County the most overvalued place in the nation for home prices. Trulia economist Jed Kolko said the county is 12 percent overvalued when comparing current prices with historical prices, incomes and rents. California took five spots on Trulia’s Top 10 list nationwide, including Los Angeles, San Francisco, Oakland and San Jose.