Bay Area single family home prices continued a skyward climb in May, reaching their highest level in more than five years, according to a report Thursday.

Median sales prices in the sizzling market were given an upward nudge in the East Bay, Peninsula and South Bay by multiple offers for a scant supply of houses for sale and by a change in the market mix to favor higher-priced homes, said real estate information company DataQuick.

Sales still are well below their year-ago levels, although they rose by double digits from April to May in Alameda, San Mateo and Santa Clara counties, and 8 percent in Contra Costa County, the San Diego company reported.

 A sale pending sign stands in front of a home for sale on February 21, 2013 in Larkspur, California. According to the National Association of Realtors.
A sale pending sign stands in front of a home for sale on February 21, 2013 in Larkspur, California. According to the National Association of Realtors. (Photo by Justin Sullivan/Getty Images) (Justin Sullivan)

"The housing market here is very hot," said Remy Weinstein, a real estate agent with Highland Partners in Montclair. "I'm just constantly amazed with the amount of overbidding going on."

Weinstein is encouraging clients to move quickly if they want to snag a home in the current torrid market.

Nick Bird, a 31-year-old catering company owner, is closing in on his first home, for $297,000 in West Oakland. "We got on it so quick we didn't have to compete with any other offers," he said. "We just paid asking price."

Bird said he was discouraged at first. "Everything's going way over asking, and you're not competing with the small guy, you're competing with investment groups that can afford to pay a little more."

Inventory is up a bit in Santa Clara County, according to Carl San Miguel, president of the Santa Clara County Association of Realtors. But in the most desired pockets of the county, it's still painfully tight.

Mi Young Lee, an agent with DeLeon Realty, has sent mailers out in Palo Alto on behalf of two families who are searching for a home to buy. One can pay $3.3 million, and the other $1.6 million to $2.2 million. Both are offering all cash.

"It's been really tight," Lee said. "There's all these multiple-offer situations. It's really bad timing for buyers right now."

Alameda County's single-family home sales had a median sales price in May of $512,000, a 24.7 percent gain from May 2012. That's the highest since February 2008. Sales were down 10.6 percent from a year earlier.

Contra Costa County's median sales price of $421,000 was up 38 percent from a year earlier, also the highest since February 2008. Sales were down 2.5 percent from a year earlier.

Santa Clara County's median price was $750,000, a 22 percent yearly gain and the highest since November 2007. Sales were down 7.3 percent from a year ago.

San Mateo County's median price was $810,000, a 29.6 percent gain over the year, the highest since November 2007. Sales were down 12.7 percent.

The total of 4,382 sales of single-family homes in the East Bay, Peninsula and South Bay in May was down 7 percent from a year ago, but up about 12 percent from April.

"Sales are just a matter of supply," said DataQuick's Andrew LePage. "We need prices to rise a bit longer to draw more people to sell their homes." In a sign of a strengthening economy, foreclosures and sales of properties worth less than their mortgages were at their lowest -- 21 percent of all sales -- since December 2007, the San Diego company said.

Absentee buyers -- mostly investors -- made a quarter of all home purchases in May, the company said.

Buyers paying in cash accounted for 27.6 percent of sales in May, down a bit from April. The monthly average back to 1998 is 13.1 percent.

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