Home prices in the U.S. in August decreased 0.4% on a month-over-month basis, the first monthly decline in four months, according to CoreLogic (CLGX). The decline was mostly seasonal in nature, the data analytics firm said. Prices were down 4.4% over a year ago, according to the CoreLogic HPI, which includes distressed sales. Distressed sales include short sales and real estate owned transactions. This follows a revised decline of 4.8% in July 2011 compared to July 2010. Excluding distressed sales, year-over-year prices declined by 0.7% in August compared to August 2010 and were down by a revised 1.7% in July 2011 compared to July 2010. “Although the calendar says August, the end of the summer traditionally marks the beginning of fall for the housing market as it begins to prepare for winter. So the slight month-over-month decline was predictable, particularly given the renewed concerns over a double-dip recession, high negative equity, and the persistent levels of shadow inventory,” said Mark Fleming, chief economist for CoreLogic. “The continued bright spot is the nondistressed segment of the market, which is only marginally lower than a year ago and continues to exhibit relative strength,” he said. Including distressed sales, the five states with the highest appreciation were  West Virginia (+8.6%), Wyoming (+3.6%), North Dakota (+3.5%), New York (+3.2%), and Alaska (+2.2%). The five states with the greatest depreciation (distressed sales included) were Nevada (-12.4%), Arizona (-10.7%), Illinois (-9.6%), Minnesota (-7.8%), and Georgia (-7.2%). Excluding distressed sales, the five states with the highest appreciation were West Virginia (+10.7%), Mississippi (+4.8%), Hawaii (+4.4%), North Dakota (+4.2%), and Kansas (+3.7%). The five states with the greatest depreciation (distressed sales excluded) were Nevada (-8.8%), Arizona (-8.3%), Delaware (-4.9%), Michigan (-4.3%), and Minnesota (-4.2%). The peak-to-current change (from April 2006 to August 2011) with distressed sales included is a negative 30.5%. With distressed transactions excluded, the HPI is down 21% during that same time period. Write to Kerry Curry. Follow her on Twitter @communicatorKLC.