pcarey@mercurynews.com

A seasonal slowdown made worse by a short supply of houses on the market had the Bay Area stuck at its lowest January for home sales in six years, according to a report Thursday.

The housing market tends to stall during the holiday and winter months, as only the most committed buyers remain. That was confirmed by the report, which was released by real estate information service DataQuick.

Sales of existing single family homes across the nine-county Bay Area fell 28.5 percent from December and were off by 16.1 percent from January 2013, the San Diego company reported.

January's sharp drop was at least partly because fewer homeowners than usual are putting their homes up for sale. Real estate agents say there are plenty of buyers, but few sellers.

But rising prices might coax more homeowners to sell in the next couple of months.

"Everything changes springtime," said DataQuick's Andrew LePage. "Traditional sellers come back into the market, and March and April are going to tell us lots more about what 2014 is going to look like."

Although the median price paid for a Bay Area single family home was $540,000, down about 5 percent from December, it was up a healthy 24.1 percent from a year ago.

Median home prices have increased steadily on a yearly basis in the Bay Area for 22 months, DataQuick said.

The median price paid for a single family home was $525,000 in Alameda. That was up 25 percent from a year ago, while sales dropped 17.2 percent. In Contra Costa County, the median price was $372,000, up 26.3 percent on a 20.2 percent drop in sales.

Santa Clara County's median price was $670,000, up 10.7 percent from January 2013, while sales dropped 14 percent drop from a year ago. In San Mateo County, the median price of $791,000 was up 23.6 percent, while sales dropped 5.9 percent from a year ago.

"We need more homes," said Rona Arjomand of ZipRealty in Palo Alto, pointing to Silicon Valley's rapid growth in jobs. "Buyers are desperately looking for properties, but nobody's selling as fast as buyers are moving in."

"The market is kind of scary for buyers," Arjomand said. "The competition is pretty much cash buyers right now. I feel bad for families living in the area for many years, and now that they have money to buy, they are getting beat by cash offers. It's a little unfair."

While the inventory of homes listed for sale is down from December in all parts of the Bay Area, it's up 13.5 percent from a year ago in Alameda County and up 34.8 percent in Contra Costa County, according to realtor.com.

That might have helped Greyson Mitchem and Raul Monares find a home to buy in Pleasant Hill. They snared a 4 bedroom, 2¿1/2 bath single family home for $825,000 that had been on the market for 45 days. They're paying less than the asking price for it.

"It's a flip," Mitchem said. "The investors want to get the most out of it they can, but I think they overpriced it."

Mitchem's agent, Sherie Corsello of Redfin, said her clients made the only offer.

"Before, everyone was experiencing multiple offers, and it was scaring buyers off. That's not so much the case any more," Corsello said, except in the market for homes over $1 million. "Maybe that's staying crazy," she said. "Inventory is still really low."

There's plenty of pent-up demand, especially at prices under $1 million, said Tom Hart of Empire Realty Associates in Danville.

"There are a lot of people out there who been renting, and with rents going up, it's provoking them to buy more quickly than they normally would."

In Contra Costa County, total home sales priced under $500,000 were down 31.2 percent, but sales above $500,000 were up 25.6 percent. Sales of homes priced over $800,000 were up 17.6 percent, according to DataQuick.

The same split -- with drops under $500,000 and increases above -- prevailed in Santa Clara County.

DataQuick said that credit appears to be easing, as reflected in an increase in adjustable-rate mortgages, which at 23.5 percent of the Bay Area's home purchase loans are the highest since July 2008.

Absentee buyers, typically investors, made up 24.2 percent of home sales in January, down from 28.3 percent a year ago, DataQuick said.

Contact Pete Carey at 408-920-5419 Follow him on Twitter.com/petecarey