AccuWeather forecasters say the hottest weather yet this season is about to grip portions of the Northwest, and the long-duration nature of the heat can put a significant strain on a part of the nation where air conditioning is not prevalent. Excessive heat watches and warnings spanned across the Interstate 5 and I-90 corridors on Saturday as locations from Medford and Portland, Oregon, to Seattle and Spokane, Washington, geared up for their hottest days yet this summer. The core of the high pre