Home prices as measured by the S&P/Case-Shiller Home Price Indices rose for the first time in eight months in April, with 13 of the 20 major markets measured posting month-to-month gains, S&P said Tuesday.

The 10- and 20-City Composite Indices were up 0.8% and 0.7%, respectively, in April versus March. Both indices, however, remain below April, 2010, with the 10-City Composite off 3.1% and the 20-City down 4.0%. The only market to register a year-over-year gain in home prices was Washington, D.C.

The indices stood at 152.51 and 138.84, respectively, at the end of April.The benchmark index of 100 was set in January, 2000.

"This month is better than last," said David M. Blitzer, chairman of the index committee at S&P. "However, the seasonally adjusted numbers show that much of the improvement reflects the beginning of the Spring-Summer home buying season. It is much too early to tell if this is a turning point or simply due to some warmer weather."

He continued, "For a real recovery we would need to see several months of increasing home prices, large enough to shift the annual momentum to the positive side. In short, better news, but still a lot of questions and a long way to go."

Washington, D.C. remained the strongest market with an index of 186.76, up 3% from March and up 4% from April of last year. Other markets with gains of more than 1% included San Francisco (132.03), up 1.7% sequentially but down 5.5% year-over-year; Seattle (135.14), up 1.6% but down 6.9%, respectively; Atlanta (101.95), which had been falling for months, up 1.6% but off 3.5%; Denver (122.32), up 1.5% but down 4.1%; and Cleveland (97.69), also a reversal of previous months, up 1.2% but down 6.8%.

In the two largest markets, there was evidence that the year-over-year declines were mitigating. New York (164.17) posted a 0.8% gain from March and only 2.8% behind April 2010. Los Angeles (168.20) was up 0.3% and 2.1% off year-over-year.

San Diego (154.50) rose 0.4% from March and was 4.3% behind April, 2010.Dallas (113.38) rose 0.5% month-to-month but was 4% below last April.Minneapolis (106.07) rose 0.4% but was the biggest loser year-over-year with an 11.1% decline. Beleaguered Phoenix (100.36) managed a 0.1% increase to remain above January, 2000 but was down 8.8% from April last year. Portland(132.84) also rose 0.1% but was 9.2% behind a year earlier.

Among the losing markets was Boston (147.07), which dropped 0.2% and was 4.2% behind last April. Charlotte (108.42) lost 0.3% and 6.6%, respectively.Chicago (110.12) dropped 0.4% and 8.6%. Las Vegas (96.94) lost 0.7% and 6.2%. Miami (136.99) dropped 0.2% and 5.6%. Tampa (126.47) fell 0.4% and 7.7%.

Detroit, the market that has lost the most value during the housing downturn, was down another 29% to an index of 62.74, 7.5% below April of last year.

The Case-Shiller Indices have historically not been seasonally adjusted.S&P recently began reporting seasonally adjusted percent changes, and by that measure, 11 markets posted declines, with most falling less than 1%.Seasonally adjusted, the Composite-10 Index was flat with March, the Composite-20 was down 0.1%.