The median single-family home price in Bellevue west of Interstate 405 fell 15.8% in August to about $3.14 million, year over year.

The decline, reported in the Northwest Multiple Listing Service's (NWMLS) August report, outpaced the broader Eastside, where the median fell 6% to about $1.45 million. Bellevue west of I-405 remained the most expensive Eastside submarket despite the slide.

The drop continued a trend visible in July, when the same submarket posted a $3.3 million median on just 21 closed sales, according to the NWMLS's July report. A year earlier, the July median was $4.3 million. The August report did not disclose how many homes sold in the submarket, and low transaction volume in luxury areas can amplify median swings.

Buyers across King County faced a similar pattern. The county's single-family median fell 7.1% year over year to $920,000. The combined median for houses and condos dropped 3.4% to $845,000.

Closed sales countywide fell 13.6%, while active listings jumped 30%.

Eastside condos also lost ground. The median condo price fell 12.2% to $630,000.

Steven Bourassa, director of the Washington Center for Real Estate Research, pointed to borrowing costs as the main drag on sales. "High interest rates continued to put a damper on the housing market in August," Bourassa said in the NWMLS report. Across the 27 counties the service covers, median prices fell 2.3% to $635,000 and closed sales dropped 7.6%.

Bourassa said he expects the Federal Reserve to raise short-term rates at its mid-September meeting, which would push longer-term rates higher. In the NWMLS's July report, published Aug. 5, he noted that rates had already averaged above 6.5% that month and predicted increases "later this year and early next year."

The 30-year fixed mortgage rate averaged 6.71% for the week ending Sept. 4, up from 6.50% a year ago, according to Freddie Mac data cited in the report. Two years ago, the same rate stood at 6.35%.