'Very hot' -- heat duration records could fall in Northwest

PORTLAND, Ore. -- Extreme heat is forecast to stretch through the weekend in the Pacific Northwest and authorities are investigating whether triple-digit temperatures were to blame for the deaths of at least four people.

The Oregon State Medical Examiner's Office said at least three people have died from suspected hyperthermia during the heat wave in Multnomah County, which is home to Portland. A fourth death was suspected due to heat in Umatilla County in the eastern part of the state.

The deaths occurred on Monday, Wednesday and Thursday. The state medical examiner's office said the heat-related death designation is preliminary and could change.

Oregon and Washington have seen scorching temperatures since July 25 and their will be no relief, forecasters say, until Monday when cool air from the Pacific Ocean blows in.

Portland and Seattle could be on track to break records for the duration of the hot spell.

Temperatures in Oregon's largest city are forecast to soar to 101 degrees Fahrenheit again on Friday. On Tuesday, Portland set daily record 102 F. Portland, too, could be on track to break a record for the duration of the hot spell

Seattle on Tuesday also reported a new record daily high of 94 F.

If temperatures rise above 90 F through Sunday in Seattle, that would be six straight days of the mercury topping 90 -- something forecasters say has never happened before in the city. Portland, too, could break heat wave duration marks.

The National Weather Service has extended the excessive heat warnings from Thursday through Saturday evening.

Courtney Lewis and Rylee Griffin were visiting Seattle this week during the hot snap.

"I mean it is nice, like to help get a tan. But it's just hot. Very hot," Griffin said.

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. The temperature at the time soared to an all-time high of 116 F in Portland and smashed heat records in cities and towns across the region. Many of those who died were older and lived alone.