The number of houses on the market drops a little in the winter.

At the end of June, the Allentown-Lehigh County Board of Realtors had about 5,200 active listings. At the end of November, the list was shorter by about 300 properties. "And in December it may go down even further," says Jim Weiss, executive officer of the board.

The numbers are similar in Northampton County. At the beginning of June, the Eastern Northampton County Board of Realtors had slightly more than 3,530 listings. Its Nov. 7 multiple-listing book had a drop of about 200.

Fewer houses come on the market because many sellers are busy with the holidays and don't want prospective buyers trooping through their houses, Realtors say.

"Traditionally, it's very slow from Thanksgiving to New Year's," says Karen Johnson, a co-owner of The Prudential Vision Realtors in Phillipsburg.

However, Realtors say, the winter is really a good time of year to list. "The average days on the market is slightly shorter in winter," says Loren Keim of Century 21 Keim Realtors in South Whitehall Township. "It's really a good time to sell."

One of the key reasons houses sell faster in winter is the low inventory. "It's a classic case of supply and demand," says Natalie Epinger, a Realtor with ERA Showcase for Living in Bethlehem, who speaks for the Eastern Northampton County Board of Realtors. "There are fewer homes on the market so there's less competition. My theory is that when the supply is down you have a great shot at selling your home."

Also, Epinger says, mortgage interest rates inevitably drop in winter, which helps to motivate buyers. At the beginning of December, the interest on 30-year fixed-rate mortgages fell below 7 percent, the lowest since the fall of 1993.

Actually, buyers who are looking for houses in the cold and snowy winter months don't need much extra motivation. "They're serious," she says. "They have to be to go out in all that mess."

Epinger remembers doing well two years ago, when the Lehigh Valley had a record snowfall and below normal temperatures. "Even in the year we had all those blizzards and getting around was rather difficult, we sold houses," she says.

Because it's cold and sometimes snowy, buyers in December and January may look at fewer houses. "They do a lot more screening behind the scenes," Epinger says. But, she adds, that can work to the sellers' advantage. Sellers, who often clean before a showing, can feel confident that buyers who venture out to see their house in winter weather are serious.

Johnson says houses are usually in their best shape around the holidays -- decorated to the hilt and ready for guests at any time. So the winter, December or Christmas in particular, can be a really good time to show a house.

Epinger says that buying a dwelling is often motivated by emotion and when the house is decorated for the holidays it can evoke good feelings. "When people walk into a home that's warm and cozy and decorated for the holidays, it could make them like the home even more," she says.

Keim says if the house has a fireplace, he'll recommend to the sellers that they light a fire to make it seem warmer. "There's a lot you can do in winter with scented candles and wood stoves and decorations. It's a fun time of year" to market a house, he says.

A favorite Realtors' tip is to bake brownies or bread before prospective buyers arrive so the house smells good and homey. That works particularly well in winter, Keim says.

Realtors say when a house is on the market in winter, it's also important to keep the walks cleared of snow and ice, and lights on throughout the house so it doesn't look dark.

Donald Senderowitz, an agent with RE/MAX in South Whitehall Township, says it's silly to take a house off the market for the winter -- although some people do. He says people are always buying. "I work with people who are transferring to the area all the time. If you take your house off the market, it's one less for them to look at," he says.

Senderowitz offers another reason why winter is ideal for buying: Some people, for tax or other business reasons, want to sell before the end of the year. Also, many relocation companies like to reduce their inventory by the end of the year. So the sellers may be more flexible on price, he says.

Also, if the owner has moved and the house is vacant, it still has to be heated. "And there's always the danger of a pipe breaking," Senderowitz says. "There may be a number of reasons the owner is more anxious to sell in winter," and may be more willing to negotiate a deal.

Besides, Senderowitz says, the key to selling a house is no different in winter than it is in spring, summer or fall. "No matter what time of the year or season, as long as you price it right, it will sell."