New single-family homes in April 2010 sold at a 504,000 unit annual rate, the highest since May 2008, 14.8% higher than the revised March rate of 439,000 homes sold, the U.S. Census Bureau and the Department of Housing and Urban Development reported Wednesday, May 26.

The unexpectedly high new home sales for April surprised economists, who had expected sales to be more in the range of 425,000 to 450,000. The joint report also stated that April 2010′s new home sales were 47.8% above the April 2009 estimate of 341,000.

Economists credited the jump in sales to the federal tax credit for first-time home buyers. The April 30 expiration of the tax credit was largely responsible for the sudden spike in sales. As a result, economists are skeptical about strength in home sales for the rest of the year.

“This data looks encouraging, but needs to be taken with a grain of salt,” said Thomas Simons, a money market economist with Jefferies & Co. in New York, in an analyst note. “The sales in this month and the upward revisions to the prior months look to be strongly influenced by borrowed future sales due to the expiring $8,000 first-time homebuyer tax credit. Sales in the last two months have risen…in spite of really no fundamental improvement in the market, especially in areas like credit availability and prices.”

While April’s big jump will result in “a wicked pullback” in the May data, Simons added, future new home sales for 2010 will nevertheless likely show that the housing market is stabilizing.

The median sales price of new houses sold in April 2010 was $198,400, and the average sales price was $249,500. The seasonally adjusted estimate of new houses for sale at the end of April was 211,000, the lowest level since 1968. This represents a supply of 5.0 months at the current sales rate, according to the report.

Read a story about March’s new home sales from the archives of InvestmentAdvisor.com.