Home sales dipped unexpectedly in May, a surprise to some analysts who predicted that the homebuyer tax credit might boost the market for some months to come.

The National Association of Realtors reports that sales of existing homes fell 2.2 percent in May, following an increase of 8.0 percent in April.

The tax credit expired April 30, but buyers have until June 30 to close. Some analysts believed the impact of the credits would linger as those contracts continued making their way through the pipeline.

Economist Peter Morici of the University of Maryland predicts that sales will taper off through the summer. He says many factors contribute to home sales including income and jobs.

“A lot of folks aren’t finding jobs,” says Morici. “Income levels are not rising. So there’s not a lot to support… more home sales.”

The good news– the NAR report says existing home sales are up significantly over the last year, rising 19.2% since May 2009.

Also today, a government report showed housing prices rose 0.8 percent from March to April.

The Federal Housing Finance Agency says the homebuyer tax credit contributed to the strength of April prices as buyers rushed to sign contracts before the end of the month.

The credit for first-time buyers was $8,000. For repeat buyers it was $6,500.

Morici predicts prices, like sales, are likely to decline this summer. “Remember there was an $8,000 subsidy that was placed on home sales,” he says. “Going forward without that subsidy, offers will be lower. Home prices will continue to slide, but not pronounced.

Morici thinks the real challenge to the housing market is “the number of foreclosures that are still waiting to happen.”

(Fox’s Julia Kimani contributed to this report)