In photos: Historic heat wave in the Pacific Northwest

A record-breaking heat wave is searing the Pacific Northwest, making life miserable for many.

Portland, Oregon, set an all-time, record-high temperature three days in a row, topping out at 116 degrees on Monday. Seattle hit 108 degrees, besting the all-time record it set just a day earlier. Across the border, Lytton, British Columbia, registered 117.5 degrees on Monday — the highest temperature ever recorded in Canada and around 48 degrees above what's normal for this time of year.

The heat has also been deadly, with many sudden deaths suspected of being linked to the extreme weather, and hundreds of people in the region have visited emergency departments or urgent-care clinics since Friday.

Kristina Dahl, a senior climate scientist at the Union of Concerned Scientists, said the heat wave is "unprecedented."

"We saw heat records over the weekend only to be broken again the next day," Dahl told CNN, "particularly for a part of the country where this type of heat does not happen very often."

Scientists have told CNN the heat wave is a clear sign of the climate crisis and that similar extreme heat events will happen more frequently in the future. Much of the Western United States is also experiencing a historic and unrelenting drought, the worst in the region in at least 20 years.