Tampa Bay home values slipped 0.6 percent from July to August to an average of $116,800, according to a report being released Friday by market tracker Zillow.com.

Nationally, home values fell 0.3 percent. Over the past year, bay area home values are down 9 percent, compared with a 3.8 percent retraction nationally, according to Zillow's estimates.

The lack of improvement in pricing, paired with increased foreclosure activity this month, likely means a delay in any market rebound, Zillow chief economist Stan Humphries predicted.

"This makes it certain that a bottom in national home values is later this year or early next year at the earliest," he said.