At least 271,300 residences in and around Portland are without an air conditioning unit, according to a 2015 survey by the U.S. Census Bureau. Homes and apartments without air conditioning make up 30 percent of Portland housing units.

Those numbers, noted by The New York Times today, are newly relevant as the Rose City stares down an unprecedented heat wave—temperatures this week could rise as high as 107, matching an all-time record, and the city could see highs above 99 degrees for four straight days. That's happened only twice before.

Census Bureau figures show 627,200 households in the Portland metro area have air conditioning, while 271,300 have not even a window unit.

Even among the "haves," some have more than others. Of those with air conditioning, 60 percent have central air conditioning with the other 40 percent getting by with one or more window units.

Still, that's better than in Seattle, where 66 percent of households have no air conditioning at all.

Portland General Electric spokeswoman Laurel Schmidt says the utility is preparing for the heat by setting up air conditioning for some of its equipment, which—like people—cannot work as hard in high heat.

She says PGE has taken steps to make sure it can handle the load and avoid a blackout.

On a personal note, Schmidt said she and her two children will be crowding into the one room in which they have a window unit.

"If that doesn't work, we'll go to my in-laws," she said.

In response to the impending heat wave, Multnomah County is opening three cooling centers until at least Monday, Aug. 7. The centers will be open weekdays from 5 to 8 pm and weekends from 2 to 8 pm. If temperatures stay over 90 degrees, the centers will continue to stay open.

The cooling centers are at these locations:

Multnomah County Walnut Park Building
5325 NE Martin Luther King Jr. Blvd., Portland

Multnomah County East Building
600 NE 8th St., Gresham

Hollywood Senior Center
1820 NE 40th Ave., Portland