Even before the remnants of Eastern Massachusetts’ snowiest winter have melted, second-home buyers flocking to Cape Cod’s beach towns have helped agent Steve Clay’s team break their sales record.

Clay, of Keller Williams Realty, said he and his four agents have 17 properties under contract, more than at any one time since the team formed in 2009

“Buyers know they missed the bottom of the market, and now they don’t want to miss the bottom of interest rates,” he said.

Second-home buyers from Cape Cod and New York’s Hamptons to Miami and Lake Tahoe, Calif., are returning to the housing market as surging stock prices, job growth, and low interest rates boost purchasing power and consumer confidence. US vacation-property sales jumped 57 percent last year to an estimated 1.13 million, a record in data going back to 2003, the National Association of Realtors said in a report Wednesday.

The increase in sales of new and existing vacation homes coincides with a 7.4 percent drop in deals for investment properties, to 1.02 million, as rising prices cut into potential profits. Purchases of owner-occupied homes fell almost 13 percent to 3.23 million, the realtors group said.

Vacation-home buyers had a median household income of $94,380, up from $85,600 in 2013, and the typical property was 200 miles away from a buyer’s primary residence. About 40 percent of purchases were in beach areas, 19 percent were in the country, and 17 percent were in the mountains.

Vacation homes accounted for 21 percent of all transactions last year, the most since the National Association of Realtors survey was first conducted 12 years ago.

‘Greatly Improving’

“We knew the fundamentals for vacation-home sales were greatly improving in 2014,” Lawrence Yun, the group’s chief economist, said in a telephone interview. “I did not expect it would be this big of an increase. It shows the buyers perceive that economic conditions will be solid for upcoming years.”

The realtors’ vacation-sales figures were based on survey responses from nearly 2,000 people who bought a residential property last year. Transactions involving institutional investors were excluded from the report.

In the Hamptons, the Long Island resort area favored by Manhattan’s elite, many people who might have rented in previous years are choosing to buy instead, said Ernest Cervi, the executive managing director who oversees Hamptons home sales for brokerage Corcoran Group. Buyers are riding high because of stock gains and average Wall Street bonuses of $172,860, up 2 percent as the industry added 2,300 jobs in New York City.

“Rates are low, so why not jump in?” Cervi said.

‘Backed Up’

Clay, who is based in Falmouth, where ferries bound for Martha’s Vineyard depart, said the snow kept many buyers away earlier in the year. In the past few weeks, the market has exploded, he said.

Single-family home sales in Barnstable County, which covers Cape Cod, rose 11 percent in February from a year earlier, according to The Warren Group, a property-data provider based in Boston.

“Mortgage people are flooded and appraisers are backed up,” Clay said. “It’s an indication that the pent-up demand is coming to fruition.”