HONOLULU -- The number of single-family homes sold on Oahu may be on a decline, but the prices of homes took a huge jump in one month's time. The Honolulu Board of Realtors released its resale figures for the month of May on Thursday.

Bank of Hawaii's chief economist Paul Brewbaker said the quick climb may last for months.

HAWAII HOUSING TOOLS: Mortgage Calculator SECTIONS: Real Estate House & Home Join Discussion

The average median sales price for a single family home last month reached an all-time high of $610,000, according to the Honolulu Board of Realtors. That's up nearly 12 percent from April.

"At $610,000 for the average home, single-family home, it's moved really fast since December. It was $495,000 in December, $550,000 in March. So $610,000, that's about a 20 percent increase in less than six months," Brewbaker said.

He said he was surprised to see such a big jump in just one month's time.

"It's probably not going to continue month-to-month like that, but it basically continues a trend that's been in place now for three, four, five years that continues unbroken," Brewbaker said.

He said it could be well into the fall before prices stabilize.

"Part of it is seasonality. May is the start of summer season. A lot of people are moving so we always observe some big numbers in May, June, July," Brewbaker said.

Brewbaker said if the sales trend continues, it is on pace for a 40 percent jump in prices in just one year. However, he admits it can't go on like this forever.

"Four to five years ago, the median was $300,000 now it's $600,000. That's a lot of move in a few years and it can only go so far before affordability makes it impossible to go further," Brewbaker said.

Condominium sales volume is down just like single-family homes, but prices are up from last month by about $20,000.