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15 million in Pacific Northwest under excessive heat warnings, advisories

Residents of the Pacific Northwest just want their daily routine -- and temperatures -- to return to normal.

Some 15 million people in the Pacific Northwest are under excessive heat warnings and advisories. That creates "a dangerous situation in which heat illnesses are possible," the National Weather Service said.

Dozens of records could be broken over the next two days. Seattle could see 100 degrees, which would be only the fourth time in recorded history. Other cities will likely see temperatures hit the triple digits.

Some models show the Seattle area by Thursday could reach or break its all-time high of 103 degrees (2009). Residents on Tuesday got a warm-up to an excessive heat warning by enduring highs near 90.

RELATED: 5 tips for staying cool at night during Seattle’s heat wave

The heat has settled in over a region where many homes don't have air conditioning. Only one-third of Seattle residents have it, while Portland's number is about 70%. Portions of Oregon are a good bit lower.

Q13 News Meteorologist Rebecca Stevenson tracked the record-breaking temperatures Wednesday morning in a Facebook Live.

Numerous cooling centers have opened.

Jillian Henze, spokeswoman for the Seattle Hotel Association, said those without air conditioning who are seeking relief will find the supply of rooms scarce. "It is our busiest season of the year; we got cruise ships and summer travel, and rooms are booked up way in advance," she said.

The National Weather Service office in Seattle said that temperatures in the region will "probably be within 5 degrees of the all-time records."

Lake Crescent over the weekend vs. Lake Crescent on Wednesday.

RELATED: Why is it so smoky in Western Washington?

Because of thick smoke from British Columbia wildfires, temperatures overnight into Wednesday did not cool off much.

Q13 News Meteorologist M.J. McDermott said Seattle's low was 69 degrees; the normal reading is 57.

Northern California will likely see peak heat Wednesday, with slightly milder temperatures on Thursday.

What's causing all of this?

A ridge formed in the jet stream -- forcing the stronger winds in the upper atmosphere well into Canada -- allowing for clear skies in the Pacific Northwest and the temperatures to rise to extreme levels. Friday into the weekend, the jet stream will flatten, allowing for temperatures to ease near normal.

Until then, police and agencies are ensuring those most vulnerable receive help. Portland police on Tuesday tried to get people who normally live on the streets into shelters or cooling centers, KPTV said.

"They really appreciate it because, literally, they are here, they don't want to walk around because it's hot out," Officer Ryan Engweiler told the station. "Just by us driving around giving them the water, giving them the information."