Metro Atlanta home prices continued to climb in May from a low, low bottom, according to a widely watched national index.

Prices were up 4 percent, beating the 2.2 percent average rise in the nation's 20 largest housing markets, according to the Standard & Poor's Case-Shiller Home Price Index.

That follows the 2.3 percent price increase posted in April, but the region continues to be the only city of 20 largest U.S. cities the index follows that has a negative double-digit annual return. Despite the improved numbers, home price are 14.5 percent lower than they were at this time last year.

"We have observed two consecutive months of increasing home prices and overall improvements in monthly and annual returns," said David M. Blitzer, chairman of the index committee. "However, we need to remember that spring and early summer are seasonally strong buying months so this trend must continue throughout the summer and into the fall."

He noted that early figures for June home starts, sales and default rates were mixed.

"The housing market seems to be stabilizing, but we are definitely in a wait-and-see mode for the next few months," he said.