December sales of single-family homes in the Seacoast area slipped to the lowest volume since April due to record low inventory, the Seacoast Board of Realtors says.

Available inventory levels were at less than half of where they were in August, according to statistics the group released Thursday.

The 70 single-family closings were off 17.6% from last month and 31.3% from last year, the group reported. As January began, there were only 56 active single-family listings in the 13-sample Seacoast towns, the lowest ever.

The 13 sample towns are Exeter, Greenland, Hampton, Hampton Falls, New Castle, Newfields, Newington, North Hampton, Newmarket, Portsmouth, Rye, Seabrook and Stratham.

December saw the year’s biggest sale at 24 Salamander Lane in New Castle (at nearly $5.7 million) raising the median sale price for the month to $621,500 up 8.1% from last year.

The 47 active condominium listings on Jan. 1 are also the lowest level ever. Condominium sales for the month were off 30.6% from last month and 38.8% from last year. The monthly median price of $409,500 was 4.7% off last year’s mark.