Holiday shoppers in Western Washington went house hunting last month, with pending sales of single-family homes increasing 18.5 percent over the same period in 2003.

In a 15-county area of the state, the Northwest Multiple Listing Service tracked 5,588 pending sales with a median selling price of $258,450.

That compares with a median price of $230,000 for the same period in 2003.

In King County, the real estate market remained red-hot, with fewer homes listed for sale.

The number of active listings fell 21 percent in King County to 4,691 single-family homes -- the fewest listings in more than a year.

That lack of inventory is driving up home prices, with the median selling price of a home in King County rising to $335,000 in December, compared with $304,700 for the same period in 2003.

Homes were on the market in King County for an average of 52 days in December, nine fewer days than in December 2003.

Pat Phillips, a real estate agent in the Madison Valley office of John L. Scott Real Estate, said buyers in the Seattle market are competing aggressively to get into homes. In one recent case, she cited a Capitol Hill condominium owner who was entertaining three offers.

"Because of the shortage of listings, you have more multiple offers, which drives the price up," Phillips said. "You have as many, if not more people, wanting to live in the hot neighborhoods. And it just goes crazy."

Mary Land, a mortgage banker with Seattle-based Evergreen Money Source, said some home seekers are eagerly trying to get into homes because they are anticipating an increase in interest rates.

"They feel interest rates are going up, and they may feel pressure to buy now instead of later," Land said. "But the reality is that interest rates are still extremely low."

On Dec. 15, the average rate on a 30-year fixed mortgage was 5.37 percent. That compares with 5.81 percent in October.