Nassau County's housing market roared to life in March after a sluggish winter. The milder weather gave Suffolk County a smaller boost.

The median price of homes in Nassau jumped year-over-year by 10.3 percent, to $419,000, and the number of sales spiked by 13.7 percent over the same period, the Multiple Listing Service of Long Island reported Wednesday.

Suffolk's gains were more modest, with the median sales price hitting $307,000, a 1.7 percent rise compared with the previous March. The number of sales grew also, by 5 percent.

There was a "tremendous amount of pent-up demand" among buyers at the end of last month, said Shawn Elliott of Woodbury-based Shawn Elliott Luxury Homes & Estates. "All of a sudden the snow melted at the end of March and they all came out in droves," he said.

Current near-record-low interest rates that are expected to rise later this year also are motivating buyers, Elliott said. The average interest rate for a fixed-rate, 30-year home loan was 3.66 percent last week, mortgage giant Freddie Mac reported.

A limited supply of homes also gives prices a boost, as buyers compete for the most desirable properties, said Steven Weizel, sales manager at Century 21 Dallow Realty in Farmingdale. In a few cases, bidding wars are driving prices up 1 to 2 percent above asking prices, he said.

There were 15,767 homes listed for sale last month in Nassau and Suffolk, 2.4 percent fewer than the previous March and less than half the peak of 32,302 in June 2008, according to listing service data.

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In both counties, last month was a busy time for prospective buyers. In Nassau, 962 homes went into contract, a year-over-year gain of nearly 7 percent. Suffolk home buyers signed 1,139 contracts, 8.2 percent more than the previous March.

The median price of pending sales in Nassau ticked up by 2 percent, to $428,225. Median pending sales prices in Suffolk made a 4.3 percent gain, to $323,300.

Real estate agents hope the momentum continues. The Long Island Board of Realtors' scheduled Open House Weekend this Saturday and Sunday "can only help attract more people," Weizel said. The sixth annual event offers a look inside 3,000 homes in Nassau, Suffolk and Queens.Those attending eligible open houses can enter a raffle to win one of three $1,500 prizes, a spokeswoman for the board said.

A list of participating real estate offices can be found at lirealtor.com/ohw.