Single-family home prices fell by double digits on Hawaii island and Kauai in September compared with a year earlier, although the number of sales increased on both islands, the Hawaii Information Service reported Wednesday.

Condominium prices also fell on both islands for the month, while sales volumes were unchanged.

The biggest price drop occurred on Kauai where the median price for a single-family home fell to $415,000 in September, a 22 percent decline from $529,500 the same month last year. There were 27 homes sold on Kauai, a 69 percent increase from the 16 sold in September 2010.

The Kauai median condo price slipped 9 percent to $235,500 in September from $260,000 a year earlier. The number of sales was flat at 20.

On Hawaii island, the median price for a single family home fell 11 percent to $224,500 in September from $251,000 a year earlier. The volume of sales rose last month to 137, a 10 percent jump from September 2010.

Hawaii island’s single-family home sales activity was concentrated in the Puna area, where 43 homes were sold compared with 42 a year earlier. North Kona was a close second with 30 sales in September compared with 34 last September.

Hawaii island condo sales were unchanged at 41. The median sales price fell 12 percent to $212,500 from $240,000.

Sales of vacant land climbed on Hawaii island, with contracts signed on 82 properties, up 58 percent from 52 properties a year earlier. The median price for a vacant parcel of land fell 15 percent to $22,250 from $26,250 in September 2010.

The median price is a point at which half the sales were for more and half for less. In small markets with relatively few sales like Kauai, the median can easily be swayed by the age, size, quality and location of homes.

For instance, in Kawaihau the median price for single-family homes was $325,000 on 11 sales last month, compared with $529,000 on nine sales a year earlier.