Case-Shiller's numbers are considered especially reliable because they measure repeat sales of individual homes. Homes sales numbers published by the Florida Association of Realtors also confirm steadier home prices since about January. Since peaking in July 2006, Tampa Bay housing prices had been on a multiyear slide.

Local home sales, measured year over year, have also improved in almost every month since September. Discounted foreclosures homes have led the way. They typically sell for half to two-thirds of the price of a nondistressed property.

The month-to-month improvement in home prices wasn't restricted to Tampa Bay. On the 20-city Case-Shiller index, only four cities showed price declines from April to May: Las Vegas, Phoenix, Miami and Seattle.

But year to year, all 20 cities recorded home price drops, with Phoenix leading the list with a plunge of 34.2 percent. Las Vegas was second-worst.

"While many indicators are showing signs of life in the U.S. housing market, we should remember that on a year-over- year basis, home prices are still down about 17 percent on average across all metro areas, so we likely do have a way to go before we see sustained home price appreciation," Blitzer said.

Most Florida economists predict home prices will stay relatively flat for at least a year and won't appreciate with any strength or consistency before 2011. Stricter lending standards, including the near-disappearance of subprime mortgages blamed for sinking the housing market, have curtailed sales.