PORTLAND, Ore. (AP) — 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 state medical examiner’s office said the heat-related death designation is preliminary and could change after further investigation. Oregon and Washington have seen scorching temperatures since July 25 and their will be no relief until Monday when cool air from the Pacific Ocean blows in.