Sonoma County's housing market got off to an uncharacteristically strong start in January with a jump in both signed contracts and completed sales.

Buyers began the year by purchasing 318 single-family homes, up 20 percent from January 2010, according to The Press Democrat's monthly housing report compiled by Pacific Union International Vice President Rick Laws.

The number of signed contracts to purchase a home jumped 42 percent, to 504 — the highest number for any month in more than three years.

Not all those contracts are expected to result in final sales in the coming months. Even so, brokers noted that the contracts involved homes in a wide variety of price ranges, not just the starter home segment where sales have been concentrated for the past three years.

Brokers maintained that the new contracts for more-expensive homes means more buyers with home equity and other assets are stepping forward after months of watching from the sidelines.

"For whatever reason, there's a lot of buyers who have put their doubts on the shelf," said Laws. He suggested one reason is that "people are beginning to believe more and more that we have hit bottom."

The county's median price stayed essentially flat in January at $322,500. It was up 2 percent from December and down 1 percent from a year earlier.

County home prices soared in the past decade and peaked in August 2005 at $619,000. Values then tumbled and the median price sank to a low for the market cycle of $305,000 in February 2009.

While sales rose last month in the county, results were mixed elsewhere. Statewide, seasonally adjusted sales fell nearly 6 percent from a year earlier, the state Association of Realtors reported Wednesday.

In the Bay Area, Solano, Alameda and Marin counties also posted double-digit jumps in year-over-year sales. But San Francisco experienced a double-digit drop in sales, and the Bay Area's other counties had modest increases or declines.

A review of the contracts signed last month shows increased activity amid a range of prices.

For homes priced below $400,000, buyers in January signed 353 deals, an increase of 46 percent over a year ago. But contracts for homes between $400,000 and $800,000 also increased 43 percent, to 123 deals. And contracts for homes above $1 million rose to 19 from 9.

The only segment where activity declined last month was between $800,000 and $1 million, where the number of new contracts declined to 12 from 19 a year earlier.

Of the homes that sold, 26 percent were foreclosures and 29 percent were short sales, where the home is sold for less than the amount owed on the mortgage. The remaining 44 percent are considered equity sales — where a bank wasn't directly involved in approving the transaction.

The new sales and contract data reflect a busier winter, brokers said, with more buyers looking for higher-priced properties. At the same time, inventory remains tight. January ended with slightly fewer than 1,100 homes for sale, the lowest number in at least three years.

For months agents have lamented the lack of starter homes for sale. But brokers said the problem now is affecting most segments of the market.

"We really are having a hard time finding properties in that move-up market" above $400,000, said Brian Connell, broker/manager for Frank Howard Allen in Santa Rosa.

Several brokers expressed hope that the higher sales and contract numbers provide evidence of a housing market that has begun to mend.

"I think we're in the midst of it," said Tim Freeman, the new manager for Coldwell Banker in Santa Rosa. "I don't think were out of the woods, but we're seeing some healthy activity."