Housing supply remained tight, demand for homes remained high, and median sales prices continued to climb last month, according to new data from the Northwest Multiple Listing Service (NWMLS), which serves 23 counties, mostly in Western and Central Washington.

The Eastside was no exception. Median sales prices of single-family homes and condominiums combined in King and Snohomish counties rose 17.6 percent and 17 percent, respectively, in September versus the same month last year, NWMLS reported.

King County’s median sales price was $698,230 and Snohomish County’s was $550,000.

The area in King County with the highest median sales price (single-family homes and condos combined) for the month was Bellevue, west of I-405, at $1.82 million on 53 closings, with Mercer Island not far behind at $1.55 million on 52 closings. Excluding condos, the medians for those markets rose to $2.7 million and $1.7 million, respectively.

Top-price markets in Snohomish County were Southeast Snohomish County, with a combined median sales price of $730,500 on 240 closings, followed by Southwest Snohomish County at $600,000 on 304 closings. Excluding condos, those markets had medians of $756,500 and $660,000, respectively.

In the Puget Sound region, only King County notched more than a month’s supply of homes, with inventory at 1.12 months. If condos are excluded, though, there were only 0.85 months of supply. Inventory indicates how long it would take to sell every active listing at the current rate of sales; the industry considers a balanced market to be four to six months of inventory. At 0.56 months of supply, Snohomish County was among three counties with the tightest inventory, with only about two weeks of supply.

In its news release announcing September’s data, NWMLS said it’s unclear if last week’s announcement from Boeing to consolidate to a single 787 production location in South Carolina, resulting in the loss of about 900 Puget Sound jobs, will dampen home sales.

“It’s too soon to make any solid predictions about how Boeing’s announcement will affect the Snohomish County housing market, but I am watching it closely,” Matthew Gardner, chief economist at Windermere, said in the release. “We could see an increase in the number of homes for sale as workers either leave the area or decide to sell to access the equity they have in their homes. If this does happen, the increased supply will likely be absorbed by buyers who currently have a limited number of homes to choose from and counter any downward pressure on prices.”

Mike Grady, president and chief operating officer at Coldwell Banker Bain, believes any impacts will be counteracted “given recent expansion announcements by Facebook, Amazon, and Microsoft to either purchase, build or renovate major office buildings in the region.”

Overall, NWMLS brokers completed 10,175 sales transactions in September — the highest monthly volume since June 2018, when NWMLS members reported 10,072 closed sales, the release said. September’s closings also marked a jump of nearly 28 percent from the same month a year ago.

James Young, director of the Washington Center for Real Estate Research at the University of Washington, said people working from home, especially those with children doing online school, seek both space and value.

“Those who already have a home have little incentive to leave,” he said in the release. He described the current scenario of “too much demand and limited supply” coupled with low interest rates as “the perfect price storm.”

In Kitsap County, there’s an extreme deficit of listing inventory heading toward the end of the year, as in other counties, said Frank Wilson, the Kitsap regional manager and branch managing broker at John L. Scott Real Estate in Poulsbo.

Wilson also reported a backlog of buyers.

“Our brokers are working with buyers who have made offers on 10 or 12 homes only to lose out to cash buyers or buyers who were willing to pay significantly more than the list price and waive all conditions, including an inspection,” he said in the release. He said brokers are bracing for an influx of buyers from King County where some residents have concerns about living in the Seattle area.

Wilson believes “more buyers in the hunt for homes in Kitsap will only intensify competition and inflate prices.”