Boise, Idaho – An early surge of summer heat is pushing temperatures up to 15 degrees above normal across much of Idaho through the end of May, with highs in Boise expected to hit 89°F by Wednesday.
According to the National Weather Service in Boise, this warm pattern will persist from Sunday, May 25, through Friday, May 30, with daily highs climbing steadily into the upper 80s and low 90s in cities like Ontario, Twin Falls, and Baker City. McCall will remain cooler but still see above-average temps, hovering in the mid-70s.
The heat is driven by a high-pressure system centered over the Pacific Northwest, with NOAA’s 6–10 day outlook showing a strong likelihood of above-normal temperatures through June 3. This early-season warmth increases fire weather concerns and may stress vulnerable populations unprepared for summer conditions.
Most areas will remain dry, but residents in eastern Oregon and Idaho’s higher terrain should watch for isolated showers and thunderstorms midweek. Drivers and outdoor workers should stay hydrated and limit exposure during peak afternoon hours.
More updates are expected if thunderstorms become more widespread or heat advisories are issued later in the week.
