The median home price in August dipped slightly to $249,000, compared with $250,000 in July and $301,000 a year earlier, according to San Diego-based MDA DataQuick.

Last month, 39,811 new and resale houses and condos were sold statewide, down from 45,079 in July but up roughly 5 percent from 37,988 a year earlier, the firm reported.

Foreclosure homes made up 40 percent of existing home sales last month, the lowest percentage during the past year. In February, they accounted for 59 percent of existing homes sold.

"We saw sales fall across the state, and we think one of the main reason is fewer low-cost foreclosures," said DataQuick analyst Andrew LePage. "That's constraining sales to some extent, as well as the ongoing weak economy. We're still climbing our way out of really deep recession, and that's impacting people's willingness to buy."

LePage said he was surprised by the magnitude of the decline, particularly because home sales have on average increased 4 percent between July and August since 1988. This year's 12 percent sales drop is the second-largest for the two-month period in the past 20 years.