Home prices improved for the sixth straight month in July but remain well below the same month last year, according to the S&P/Case-Shiller Home Price Indices released Tuesday.

The 10-City Index, covering the largest metro areas, rose 1.7%, and the 20-City Index was up 1.6% from June to July on a non-adjusted basis, S&P said. Seasonally adjusted, the gains were 1.3% and 1.2%, respectively.

Both indices remain well below July, 2008, the 10-City down 12.8% and the 20-City down 13.3%. However, all 20 metro areas also showed improvement in annual rate of decline. The data beat Wall Street expectations of declines in the 14.2% range.

"The rate of annual decline in home price values continues to decelerate and we now seem to be witnessing some sustained monthly increases across many of the markets," said David M. Blitzer, chairman of the index committee at S&P. "These figures continue to support an indication of stabilization in national real estate values, but we do need to be cautious in coming months to assess whether the housing market will weather the expiration of the federal first-time buyer¹s tax credit in November, anticipated higher unemployment rates and a possible increase in foreclosures."

Average home prices across the country in July were back to autumn, 2003 levels. From the peak in the second quarter of 2006, the 10-City is down 33.5% and the 20-City down 32.6%.

Among the biggest sequential gainers were Minneapolis (+4.6%), San Francisco (+3.3%), Chicago (+2.7%), San Diego (+2.5%) and Atlanta (+2.3%). Of the remaining metros, only Seattle and Las Vegas showed monthly declines, down 0.1% and 1.1%, respectively, with the rest all up between 1% and 2%.

Compared to July 2008, the hardest-hit markets include Las Vegas (-31.4%), Phoenix (-28.5%), Detroit (-24.6%), Miami (-21.2%), Tampa (-18.4%), San Francisco (-17.9%) and Minneapolis (-17.3%). The best performers were Cleveland (-1.3%), Dallas (-1.6%) and Denver (-2.9%). Among the rest, Atlanta was down 11.8%, Boston down 4.9%, Charlotte down 9.0%, Chicago down 14.2%, Los Angeles down 14.9%, New York down 10.3%, Portland down 13.9%, Seattle down 15.3%, San Diego down 12.3% and Washington down 9.8%. Las Vegas in July hit a new low since its peak in August of 2006, resulting in a 54.8% peak-to-trough decline.