There were 28,871 houses and condominiums sold in January - still around 9 percent below the January average, despite the year-over-year improvement, DataQuick reported.
Sales also were sharply down from December but that is normal for the season, the firm said.
"Indicators of market distress continue to decline," the company said in a statement. "Foreclosure activity has been trending lower and remains well below peak levels reached several years ago. Financing with multiple mortgages is low, while down payment sizes are stable."
The median price paid for a home was $290,000, up nearly 23 percent from January 2012. January also marked the 11th consecutive month in which the median price rose compared with the same month a year earlier.
Another good sign was that foreclosed homes accounted for fewer than a fifth of home sales - down from more than a third a year earlier.
Short sales - transactions in which the sale price was lower than what was owed on the property - dropped fractionally but still comprised more than a quarter of all sales.
DataQuick earlier reported that both Southern California and the San Francisco Bay area posted their strongest January homes sales in six years. Median home prices also surged in both regions.
However, DataQuick President John Walsh said the apparent recovery is still shaky.
Absentee buyers, mostly investors and second-home buyers, bought well over a quarter of the homes in both northern and southern regions - in both cases, the highest figure since DataQuick began keeping absentee statistics in 2000.
"The mortgage market is still dysfunctional," he said in a statement earlier Thursday that accompanied the Northern California figures. "That said, the market imbalances are moving toward normalcy."
Lower mortgages may be continuing to fuel the market.
The typical mortgage payment for California home buyers last month was $1,030. That was up from $906 a year earlier but still more than 63 percent lower than a 2006 peak and around 55 percent below a 1989 peak, DataQuick reported.
The Associated Press contributed to this report.