They were small, but price gains achieved by Oahu’s housing market last month continued a rising trend reaching further into its third year.

Data released by the Hono­lulu Board of Realtors for publication Monday showed that median prices for previously owned single-family houses and condominiums sold in March rose 3 percent over the same month last year.

Single-family houses sold for a median $657,000 last month, compared with $640,000 a year earlier.

Condos sold for a median $350,000, compared with $340,000 in the same period in 2013.

Home prices on Oahu have been on a modest upswing since 2012, driven by factors that include rising personal income and job growth, low interest rates, relatively little new housing construction and tight inventory of existing homes for sale.

The University of Hawaii Economic Research Organization said in a report released late last month that the supply-and-demand balance is particularly under pressure from rising income that leads to the formation of new households that need housing.

"These sources of housing demand will push up against available supply, leading to an acceleration of Oahu home prices to high single digits this year and next," the report said.

UHERO also noted that despite a condo development boom in Kaka­ako, there is significant doubt that construction on Oahu will produce the 4,000 new homes required annually to keep up with population growth.

One drag on the housing market is expected to be rising interest rates. UHERO pro­jects that the average interest rate on a 30-year mortgage will edge up to 4.6 percent this year from 4 percent last year, and then top 5 percent in 2015.

Given some recent moderation of growth in parts of the local economy, such as tourism, UHERO dialed back its projected median home price increases a bit in its latest report. The organization forecasts a 9.8 percent increase for single-family houses compared with about 12 percent in a prior report.

The forecast for condo median price growth is 6.2 percent, down from about 7 percent.

For the first three months of this year, the median sale price for single-family houses is up 9.2 percent at $655,000, while the condo median is up only 1.5 percent at $345,000.

One area of weakness in the market last month was the number of condo sales, which declined 6 percent to 387 from 411 a year earlier. For the first three months of this year, condo sales are up 2 percent to 993 from 976 in the same period last year.

Single-family house sales were up 7 percent to 246 in March from 231 a year earlier. For the first three months of the year, sales are up 2 percent to 682 this year through March from 669 a year earlier.