That has been changing rapidly throughout the region. There’s been enough extreme heat waves over the past decade that AC is becoming normalized. Just about any new build is going to have it now. Especially in the Portland or Seattle areas where most people in the region live, the Summers now often also have smoke from forest fires so opening a window for a breeze may not be ideal.

In the Willamette Valley (main population area) most people have some type of air-conditioning. Just a window unit on some of the older construction. Around 20% of the homes have no cooling.

The state is pushing for heat-pump adoption on all newer builds or furnace replacements. Both for energy savings and to meet the cooling needs from increasing temps.

https://www.oregon.gov/energy/Data-and-Reports/Documents/2023-Oregon-Cooling-Needs-Study.pdf