House prices in the Twin Cities metro area posted the second-biggest month-to-month increase during May, but the biggest annual decline in the nation, according to the latest Case Shiller home price index.

The report tracks prices as part of a 10- and 20-city composite, which showed house price increases of about 1 percent in both indexes from April to May.

In the Twin Cities prices were up 2.6 percent from April to May, the second-biggest increase of all 20 metro areas.

Year-over-year, prices in the Twin Cities fared the worst, falling 11.7 percent from May 2010.

Home prices typically rise during the late spring and early summer, which is peak buying season as families focus on trying to move by the time school starts in the fall. That's especially true in cold-weather markets like the Twin Cities, where winter makes shopping for a house less appealing.

David Blitzer, chairman of the Index Committee at S &P Indices, attributed the national month-to-monthincreases to seasonality. ""This is a seasonal period of stronger demand for houses." Prices increased in 16 of the 20 cities, but fell in Detroit, Las Vegas and Tampa. Compared with May 2010 prices this year were down in 19 of 20 cities.