Where are all the houses for sale?

That's the question that homebuyers and their real estate agents are asking, as a report Thursday showed February home sales hit a six-year low around the Bay Area.

While factors ranging from credit to affordability can depress sales, "the main culprit is an inadequate supply of homes for sale," according to real estate information service DataQuick.

While prices jumped, sales of single-family homes dropped an average of 10.5 percent around the nine-county Bay Area, with dips of 15.3 percent in Contra Costa County and 19.5 percent in Alameda County, DataQuick reported. Santa Clara County held its own with a 1.9 percent gain, while San Mateo County was up 8 percent.

But sales in those four counties were well below the average February in DataQuick's records, which begin in 1988.

The median price paid for a single-family home in Alameda County was $500,000 in February, up 24.4 percent from a year ago; $401,000 in Contra Costa County, up 31.5 percent; $724,000 in Santa Clara County, up 15.8 percent, and $765,000 in San Mateo County, up 10.5 percent.

The stock of homes for sale typically rises at this time of year. Listings were up from a year ago in Alameda and Contra Costa counties and down in Santa Clara and San Mateo counties, according to Realtor.com. All four counties showed gains from January.

It's still far from normal. "We're still way down from where we were two years ago," said David Stark, spokesman for Bay Area East Association of Realtors.

So far this year, the market appears to be a "virtual carbon copy" of the housing market last year that sent prices soaring in the spring, according to Michael Seguin at the Contra Costa Association of Realtors.

Rising prices are expected to coax more sellers off the fence in April and May.

That's the hope of Brenna Santos, 25, of San Jose, who has been looking for her first home -- a condo -- since December. "It's been really difficult to find something," said Santos, an AT&T sales agent who has been outbid several times.

"Some of the nice ones were getting taken so fast I didn't have a chance," Santos said. "It's very, very competitive."

Some of the homes in her price range weren't in great shape, she said. "It was, gosh what happened here? It was completely missing a door and had some old food in the pantry and the carpet was ripped up."

Her agent, Jason Von Raesfeld, said Santos has an FHA loan, popular with first-time buyers, but is competing against all-cash buyers.

Not surprisingly, sellers are cleaning up.

In the South Bay cities of Cupertino and Sunnyvale, homes were fetching $200,000 to $300,000 over asking price, according to sales figures compiled by Mark Wong of Alain Pinel Realtors in Saratoga.

That's true in Palo Alto, too. Jack and Mary Spence put the 1,200-square-foot Palo Alto home they'd lived in for 20 years on the market for $1.295 million recently. It sold for $1.7 million.

"It was way more than what we expected," said Mary Spence.

Instead of downsizing, the retired couple were able to "upsize" to a 3,400-square-foot home in Lodi.

In Dublin, Jeremy and Megan Brotherton, both 30, have put their home up for sale. They're asking $649,000 and have been swamped with buyers. They were out of town for their first open house, but a neighbor "said it looked like we were having a huge party," said Megan Brotherton. "Cars were lining the streets. He sent me a text saying, 'Man there's a lot of people at your house!'"

But the flip side is that once they sell, they will have to find something to buy.

As part of their home sale, they are asking to rent back the house for a couple months while they look for a home in Danville or San Ramon. "Otherwise we will be looking for a month-to-month rental place at a Courtyard Marriot or a Residence Inn," she said.

"Things are going very quickly," Jeremy Brotherton said. "The last home, we offered above the list price, but they had multiple offers." On another they're making an offer on, the seller's agent said they're anticipating six to eight offers.

With prices rising, the number of homes and condos that sold for less than $500,000 fell 30 percent from a year ago, while homes that sold for more than that increased almost 71 percent, according to DataQuick.

The median price fetched by a resale single-family home was $555,000 in the nine-county Bay Area, up from $540,000 in January.

Distressed sales -- foreclosure resales and short sales -- were 12.4 percent of February's sales, down from 34 percent a year ago.

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