Boise hit 100° for the 5th day in a row on Sunday. One more day of triple-digit heat is ahead for the Treasure Valley before temperatures return closer to normal.
As the high pressure ridge responsible for the extreme heat moves further east, a low pressure system off of the Pacific coast will move towards the Pacific Northwest. It will bring cooler air to the region by Tuesday with highs closer to normal. Before that, the wind will begin to pick up late Sunday night into Monday throughout the region.
A Red Flag Warning is in effect for the Owyhee Mountains in southwestern Idaho and Malheur and Harney counties in southeastern Oregon through 9:00 PM Monday. Very low relative humidity coupled with gusty winds will lead to rapid spread of any fire starts. The strongest wind gusts will be Monday afternoon and evening (30-40 MPH gusts) as a cold front approaches the region.
Behind the cold front, temperatures will be about 5-10° cooler. Tuesday's afternoon highs will be in the mid 90s in the Treasure Valley, lower 90s in the Magic Valley, and upper 70s and lower 80s in higher elevations.
Throughout the rest of the week, temperatures remain fairly consistent with increasing chances for mountain thunderstorms later in the week.
