There is high confidence in a dangerous heat wave in the Pacific Northwest, with locations in the interior valleys and lower elevations of western Oregon facing one of their hottest five-day stretches on record (by average temperature), with above 38 °C (100 °F) highs likely.

A dangerous heat is expected for portions of the Northwest United States beginning on Sunday, August 13, 2023, and continuing through August 16 or 17.

The heat wave is mainly expected in western Oregon, southwest Washington, and the Columbia Basin, the NWS Weather Prediction reports.

A relatively long duration of four to five days, and very warm overnight low temperatures, may increase the health risks compared to a more typical heat event.

The greatest risk exists in the interior valleys and lower elevations of western Oregon, including Portland, Salem, Eugene, other locations in the Willamette Valley, and Medford. The persistence of the heat and warmth overnight are likely to lead to one of the hottest (by average temperature) five-day stretches on record in these areas.

Heat levels are expected to begin increasing this weekend, NWS said. “Now is the time to begin to put your heat plans into action. This is particularly true for anyone without reliable access to cooled and air-conditioned locations, and anyone with plans for outdoor recreation. Have a way to break your heat exposure and stay hydrated!”