Oregon authorities are investigating four additional deaths potentially linked to last week’s scorching heat wave, bringing the total number of suspected hyperthermia deaths to 14.

The Oregon State Medical Examiner’s Office said Monday the designation of heat-related death is preliminary and requires further investigation.

Multnomah County, which is home to Portland, recorded seven deaths suspected to be related to heat, the highest of any Oregon county.

Also read: Dangerous Pacific Northwest heat wave suspected in 6th death

Portland and Seattle set records Sunday for most consecutive days of high temperatures.

In Portland, temperatures on Sunday rose above 95 degrees Fahrenheit (35 Celsius) for the seventh day in a row, a record for the city for consecutive days above that mark. Further north in Seattle, the temperature rose to 91 F (32.8 C) by early afternoon, marking a record six days above 90 F (32.2 C).

Temperatures neared the triple digits nearly all of last week in the Portland area, prompting officials to open emergency overnight shelters and cooling stations.

The National Weather Service issued an excessive heat warning for both the Portland and Seattle regions lasting through late Sunday evening. Temperatures started to cool off on Monday as colder air from the Pacific blows in.

Also read: Northwestern US heat wave could have hottest day on Tuesday

Climate change is fueling longer heat waves in the Pacific Northwest, a region where weeklong heat spells were historically rare, according to climate experts.

Residents and officials in the Northwest have been trying to adjust to the likely reality of longer, hotter heat waves following last summer’s deadly “heat dome” weather phenomenon that prompted record temperatures and deaths.

About 800 people died in Oregon, Washington, and British Columbia during that heat wave, which hit in late June and early July of 2021. The temperature hit an all-time high of 116 F (46.7 C) in Portland.