Home prices in June rose for the third consecutive month, but the gains are likely driven by seasonal upswings rather than a more fundamental improvement the nation's housing conditions, FNC Inc. reports. Single-family home prices increased 0.9% in June, according to the company's residential price index, which covers existing and new home sales, but excludes foreclosed homes. June's uptick follows a 0.8% rise in May and a 0.5% boost in April. All three RPI composites (the national, 30-MSA, and 10-MSA indices) show month-over-month increases the last three months, rising more rapidly in June at 0.9%, 0.7%, and 1.5%, respectively. Since March, seasonal upswings resulted in a 2.1% improvement in home prices nationwide, FNC said. Among the metro areas tracked by the 30-MSA composite, there was a 50-50 split in June between markets with monthly increases and those with declines from the prior month. Boston, Chicago, Cleveland, Denver, Detroit and Nashville, Tenn., posted higher prices in April, May and June, with gains averaging between from 0.6% to 3.5%. Boston in particular, enjoyed an extended rebound with prices going up 9.1% in the first half of 2011. Cincinnati and Columbus, Ohio; Minneapolis; Nashville; and San Francisco also showed robust year-to-date price trends, rising between 4% and 5% since January. Las Vegas and Orlando, on the other hand, lead the nation in price declines, down 5.9% and 4.1% respectively since January. Orlando is down 15.8% compared to a year earlier and Las Vegas is down 12.5% from 2010 prices. Others with a 10% or more decline in home prices from a year ago include Atlanta, Sacramento, Calif.; and Tampa, Fla. Write to Kerry Curry. Follow her on Twitter @communicatorKLC.