Heat turns dangerous by late week for Portland and entire state

PORTLAND, Ore. (KOIN) – High pressure starts flexing its muscle Wednesday. That means we're pumping up temperatures to nearly 90° the afternoon.

Consider it a training day for the major heat we're expecting on Thursday. A Heat Advisory, issued by the National Weather Service, will go into effect starting Thursday at 11 a.m. and last until 11 p.m. This includes the entire Willamette Valley and Rogue Valley down to the California border. Temperatures will swell to nearly 100° for Portland. If we hit 98° that will be a record tie for that day in the Rose City.

Hot and humid weather is expected across Southwestern Oregon, possibly up to 105° Thursday and Friday. This heat will be followed by an increasing chance for thunderstorms by the weekend for Southern and Eastern Oregon.

Neither heat nor thunderstorms are good for firefighting efforts. More active fire behavior is expected by the end of the week. Be aware that air quality conditions in your area may change as wind direction shifts under this ridge of high pressure.

Be prepared with an emergency kit any time of year when traveling, especially during the summer wildfire season. Extreme heat is the number one killer in the United States claiming more lives than floods, hurricanes and tornadoes. Heat will sneak up on you. Know the heat illness symptoms.