Oregon and Southwest Washington are heading into a stretch of dangerous summer heat, with forecasters warning of triple-digit temperatures and increased health risks beginning this weekend and peaking early next week.

The National Weather Service offices in Portland, Pendleton and Medford are all predicting a shift from the recent cool, cloudy weather. Starting Thursday, skies will clear and temperatures will begin rising across the state.

While Thursday and Friday will remain relatively mild, with highs in the 70s and 80s for most of Oregon, the heat will build rapidly.

Coastal areas south of Cape Blanco, particularly around Brookings, will begin to warm earlier due to the Chetco Effect, a downslope wind pattern known to cause sharp temperature spikes.

By Sunday and Monday, large portions of the state are expected to experience extreme heat, with temperatures soaring past 100 degrees Fahrenheit in many inland areas. High pressure building over the Pacific Northwest will push temperatures to their peak during this period.

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Here’s what to expect:

• Portland and the Willamette Valley have a 60–85% chance of reaching 100 degrees or higher.
• Medford is forecast to hit 106 degrees, with a 40% chance of reaching 110 degrees.
• Eastern Oregon, including the Columbia Basin and inland valleys, will see highs in the mid-90s.

Eastern Oregon will also remain breezy and dry, with a few lingering showers possible Thursday morning in the northeast corner of the state.

While fire danger remains low for now, officials expect fire weather concerns to increase as conditions dry out and temperatures rise.

Adding to the NWS, overnight lows in many urban areas — including Portland and the northern and central Willamette Valley — may not fall below the mid-60s. These warmer nights increase the risk of heat-related illnesses.

Health officials say heat illnesses are preventable and that knowing the warning signs can help save lives. Drinking plenty of fluids, staying cool indoors and wearing light clothing are some ways people can prevent heat illness.

Temperatures will be heating up Sunday into early next week! With the potential for high temperatures in the mid to upper 90s, it will be important to practice heat safety, especially for those who have outdoor plans or are vulnerable to the heat. #ORwx #WAwx pic.twitter.com/PGWaXpkRsZ

— NWS Portland (@NWSPortland) August 7, 2025

News Source : https://www.opb.org/article/2025/08/07/oregon-dangerous-heat-wave-weekend-next-week/