Oahu housing prices appear pretty certain to rebound from a two-year slump this year.

September marked five straight months of median price gains for single-family homes on the island when compared with prices in the same months last year. The number of sales also continued a somewhat consistent string of increases.

The Honolulu Board of Realtors reported yesterday that the median price for previously owned single-family homes sold last month was $622,450. That was up 2.9 percent from $605,000 in September 2009.

For the first nine months of the year, the median price is $599,000, or 4.2 percent higher than it was at the same point last year.

Given the typical number of sales per month, it seems unlikely that activity in the last three months of this year can reverse what’s on pace to be a full-year gain for the median home sale price.

A gain would end two years of median price declines — 3 percent in 2008 and 8 percent last year.

The University of Hawaii Research Organization earlier this month forecast that Oahu’s median home price will rise 4.4 percent this year, and continue rising between 4 percent and 5 percent in each of the next two years.

"To me the time is now to buy if you can," said Anthony Paresa, an engineer who bought a house in Hawaii Kai last month.

Paresa said interest rates are at a phenomenal low, and prices are starting to creep up from the two-year trough.

"It’s an opportune time," he said.

The market continues to exhibit resilience in avoiding a hangover effect from the rush of buying earlier this year driven by a federal stimulus program that enticed home buyers with tax credits. A sizable foreclosure inventory also hasn’t dragged down median prices significantly.

Inventory overall has remained relatively light, which is fueling competition among buyers for well-priced homes. There were 1,515 single-family homes on the market at the end of September, which compared with 1,711 a year earlier and 2,389 two years ago.

Low interest rates and home prices that are still lower than they were three years ago also have helped drive sales.

There were 274 single-family homes bought last month, up 8.3 percent from 253 a year earlier.

For the first nine months of the year, the number of sales is up 20 percent to 2,251.

In Oahu’s condominium market, the number of sales was down 15.8 percent to 298 last month from 354 a year earlier. But year-to-date, sales are up 21 percent to 2,937.

The median sale price for condos last month was $335,000, up 8.2 percent from $309,500 a year earlier. But year-to-date, the median price is unchanged at $305,000.

UHERO projects the condo price will eke out a 1 percent gain this year, then rise around 5 percent in each of the next two years.