The median price for single-family homes sold on Oahu dipped a bit for a second consecutive month in January, edging down 3.9 percent to $595,000 from $618,900 a year ago, according to a Honolulu Board of Realtors report released today.

Last month’s decrease followed a 0.8 percent dip in December after a year of mostly moderate increases that put the median price for all of 2012 at $620,000 and up 7.8 percent.

Condominium prices continued their positive run for a seventh straight month, rising 3.3 percent to $315,000 in January from $305,000 in the same month last year.

Kevin Miyama, president of the trade association and an agent with Prudential Locations, said the median price for single-family homes in January was dragged lower due to an increase in the proportion of mid-priced and lower-priced home sales.

The median price is a point at which half the sales are for a higher price and half for a lower price, so the measure can be swayed by more transactions at the high or low end.

There was a 30 percent surge in the number of single-family home sales last month, to 227 from 175 a year earlier.

Miyama said many first-time homebuyers, who typically buy lower-priced homes, were responsible for the big gain that had a negative effect on the overall median price.

The number of condo sales rose 6 percent to 286 from 270 in the same period.