NEW YORK (AP) - Home prices rose for the third straight month in August, a key ingredient for a broad and sustained housing recovery.

The Standard & Poor's/Case-Shiller home price index of 20 major cities climbed one percent from July to a seasonally adjusted reading of 144.5. While prices are down 11.4 percent from August a year ago, the annual declines have slowed since February.

The index, released yesterday, showed a widespread turnaround with prices rising month-over-month in 15 metro areas since June. San Francisco, Minneapolis and San Diego led the way.

Prices are at levels not seen since August 2003 and have fallen almost 30 percent from the peak in May 2006. Many economists also expect a double dip in prices. Despite signs the economy is recovering, home prices could decline again as unemployment and foreclosures rise and a tax credit for first-time homebuyers expires next month.

Zach Pandl, an economist at Nomura Global Economics, expects prices to fall to the lows reached earlier this year before recovering in early 2010.

"We need to see flat to rising prices in the winter months," Mr. Pandl said. "That would be a very encouraging sign that prices have bottomed out."

Low prices and mortgage rates combined with the tax credit have spurred sales. Home resales climbed more than nine percent in September, the largest amount in more than 26 years, the National Association of Realtors said last week. Sales figures for newly built homes are due out Wednesday.

Jacqueline Buchanan picked up a two-bedroom bargain foreclosure five miles from her work in Miami. She plans to qualify for the federal tax credit and spend the money on her new home.

"You want to know how good of a deal it was? In 2007, the property sold for $449,000 and I got it for $71,000," said the 50-year-old nurse, who moved here from England more than two years ago. "And it's immaculate."

Though prices in Miami have edged up for three months in a row, they are about half the level they were in 2006, according to the Case-Shiller index.

Congress is considering extending the tax credit that saves first-time buyers 10 percent of the sales price, up to $8,000. This week, top Democrats in the Senate pressed a plan that would prolong the credit but gradually phase it out over the next year.

Supporters will likely point to new data yesterday that showed confidence about the US economy declined unexpectedly in October. With job prospects bleak, the Conference Board's Consumer Confidence Index fell almost six points from September to the lowest level since May.

And home prices are not rising everywhere.

Prices in Las Vegas, Seattle and Charlotte, North Carolina, all fell to their lowest levels in August. Prices in Las Vegas have plunged by 56 percent since peaking in April 2006, the largest peak-to-trough decline of all 20 cities.