The figures are based on Multiple Listing Service data of all homes sold for more than $1 million last month in Alameda and Contra Costa counties.
A total of 160 luxury homes sold last month, up from 126 transactions in December 2012. High-end sales were down from November's 199 units, but a decline from November to December isn't unusual.
Meanwhile, the median sale price of a luxury home in December rose to $1,310,500, up 6.3% from a year ago when the median stood at $1,232,000 and up 4.8% from the previous month when it was $1,250,000.
The upper end of the market was especially strong with 17 sales of more than $2 million, more than double the seven multi-million-dollar transactions at the same time last year.
Other key market indicators were mixed last month with sellers receiving a higher percentage of their asking price on average, but homes taking slightly longer to sell than they did a year ago.
"The East Bay's luxury housing market had a great year in 2013 with sales increasing consistently on a year-over-year basis, especially in the upper end of the market, and prices moving steadily higher," said Rick Turley, president of Coldwell Banker Residential Brokerage. "The only thing that kept sales from going even higher was the severe shortage of homes on the market."
"We continue to have an imbalance between the supply of homes and the extremely strong demand from buyers in Alameda and Contra Costa counties," he said. "There are signs that is gradually starting to change with more inventory expected to come on the market in the weeks ahead. Hopefully that will bring the market back into a healthier balance in 2014, which will be good for everyone -- buyers and sellers alike."
Some key findings from this month's Coldwell Banker Residential Brokerage luxury report:
* The most expensive sale in the East Bay last month was a three-bed, four-bath approximately 4,350-square-foot home in Orinda that sold for $3,376,250;
* Danville boasted the most luxury sales with 26, followed by Berkeley with 19, Fremont and Pleasanton with 15, and Alamo and Lafayette with 11 each;
* Homes sold in an average of 52 days, up from 51 days a year ago and 35 days the previous month;
* Sellers received an average of 102.5% of their asking price, up from 99.6% a year ago but down from 103.9% the previous month.