Portland's summer, which has been fairly mild up to now, will take a turn toward oppressive, as the region begins a multi-day heatwave due to strong high pressure moving northward from the desert Southwest.
The National Weather Service expects most inland valley locations will see temperatures of 98-103 degrees Friday and Saturday.
Portland and most valley locations are under an extreme heat warning beginning 11 a.m. Friday and extended through 5 a.m. Tuesday.
Heat-related illnesses increase when temperatures are this hot and can be significant to those who must work outdoors, or whose living spaces lack adequate cooling.
Multnomah County had not announced open cooling centers as of early Friday morning. Check this website for up-to-the-minute information on cooling centers: multco.us/programs.
The Portland downtown core started Friday in the mid-to-upper 60s and will only get hotter from there. The high temp estimate is 101 degrees. This would break the date record of 98 degrees set in 1943.
Portland will also see some gusty winds at times, especially on the east side near the Columbia River Gorge.
Overnight lows will continue on the warm side with most locations struggling to dip below the upper 60s by Saturday morning. Temps in the gorge may not fall below the 70s.
Saturday should bring the fiercest heat with a high of 103 likely. The record high heat on August 23 is 101 set in 1988.
Sunday will be the third day in this stretch with temps near 100. The official forecast high will be 99, as models are showing a 75-95% chance of temps exceeding 95 degrees Sunday and Monday.
Monday's high should fall a degree or two into the high 90s and Tuesday will be much the same.
Current long-range guidance doesn't see any chance of the ridge of high pressure breaking down until around Thursday. Make plans now for an extended heat wave that could be an extreme hazard to those who lack appropriate cooling appliances.