The Heat Dome: Deadly hot weather descends on Pacific Northwest.

Thirteen million people in the Pacific Northwest will contend with a historic heat wave.

70-79 F// 80-89 F// 90-99 F// 100+ F NOAA

This Sunday could be the hottest day on record in Portland, Oregon, as 13 million people across the Pacific Northwest brace for record heat. 

“We’re taking this very seriously as a public health emergency because of the prolonged nature of it,” says Dan Douthit, the public information officer for the Portland Bureau of Emergency Management. 

Portland isn’t a stranger to hot summers that push temperatures into the upper 90s and occasionally break 100 degrees Fahrenheit, says Douthit, but sustained triple digits is rare for the city, where heat could reach 110°F this weekend and into next week. 

The core of the heat dome, as measured by the thickness of the air column over British Columbia and the Pacific NW, is – statistically speaking – equivalent to a 1 in 1000 year event or even 1 in 10,000 year event.

“A heat dome is basically that trapping dome. The heat event itself is the heat wave, lasting several consecutive days and nights that are well above normal,” she notes, adding that the heat dome helps sustain the heat wave.

Bair says it’s common for areas of high pressure to sit over the West during both winter and summer months, but “It is unusual to have heat events this early.” 

Last week, a heat dome created extremely hot conditions for the Southwest, breaking temperature records. It reached 123°F in Palm Springs and Las Vegas saw a record high of 114°F.

“It’s the same high-pressure pattern we’ve had parked over the West; it just kind of moves north and south or east and west. It moves and strengthens and weakens,” says Bair.

Source: National Geographic CBS and the NOAA