Boise, Idaho – Much of southern Idaho is set to bake under a dome of high pressure this week, with temperatures rising into the 90s and little relief in sight by the weekend.
According to the National Weather Service in Boise, a weak high-pressure system early in the week will give way to stronger ridging, pushing highs into the low- to mid-90s by Sunday, June 29. The warming trend begins Monday and accelerates by midweek, with cities like Boise, Caldwell, and Twin Falls expected to reach 94–95°F on Sunday.
Caldwell and Mountain Home will see daily highs near or above 90°F starting Wednesday. McCall remains cooler, but even this higher-elevation area will climb into the mid-80s by Friday. Overnight lows throughout the week will range from the 40s in McCall and Baker City to the upper 50s in lower valleys like Nampa and Ontario.
Residents are advised to stay hydrated, limit outdoor activities during peak heat hours, and check cooling centers if needed. The dry pattern increases fire risk, particularly in grassland regions.
Temperatures are expected to peak Sunday, but elevated heat may linger into the following week. No rain is expected.
