A Heat Advisory is in effect for lower elevations of southwest Idaho and southeast Oregon Friday and Saturday as a broad upper-level high pressure system expands into the region, pushing temperatures to dangerous levels.
A broad upper-level high pressure centered over the Rocky Mountains will expand into the region Friday and Saturday. The resulting warming will push temperatures to around 100 degrees across lower elevations, including the Snake River Plain and Weiser River Basin. After Friday's heat, warm overnight lows will limit recovery for those without a way to cool down. The heat peaks on Saturday with much of the advisory area reaching 100 to 103 degrees, while locations around Glenns Ferry could push to 105 degrees. Winds will pick up Friday afternoon, with the heat low enhancing the evening wind push through Baker County. Saturday will see broader coverage of breezy conditions as increasing southwest flow aloft mixes to the surface.
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Continued hot conditions are expected through the extended period, running 4 to 8 degrees above normal under high pressure aloft encompassing the entire Great Basin, Rocky Mountains, and northern Plains states. An upper trough in the Gulf of Alaska will bring gradual cooling Tuesday through Thursday as it moves onto the northwest coast.
Southwest flow aloft will transport mid and high-level monsoon moisture over Oregon Monday and Tuesday, and Idaho Tuesday and Wednesday, for a slight chance of thunderstorms. Initial storms will bring gusty winds and little rain, while later storms will be wetter, especially Wednesday, as moisture values climb to the 95th percentile relative to climatology. The concern will gradually shift from fire danger Monday and Tuesday due to lightning on dry fuels, to flash flood potential by Wednesday.
Residents should take this heat seriously. Stay hydrated, limit strenuous outdoor activities during the hottest parts of the afternoon, use air conditioning or visit a cooling center, and check on vulnerable neighbors and family members. Never leave children or pets in parked vehicles.
Tonight
Clear, with a low around 67. Light wind.
Saturday
Sunny and very hot, with a high near 102. Light wind but could gust as high as 20 mph briefly.
Saturday Night
Increasing clouds, with a low around 68. Light wind..
Sunday
Partly sunny and hot, with a high near 99. Light wind.
Sunday Night
Mostly cloudy, with a low around 69. Light wind..
Monday
Mostly sunny and hot, with a high near 101.
Monday Night
Mostly cloudy, with a low around 70.
Tuesday
Partly sunny and hot, with a high near 97.
Tuesday Night
Partly cloudy, with a low around 66.
Wednesday
Sunny and hot, with a high near 99.
Wednesday Night
Mostly clear, with a low around 66.
Thursday
Sunny and hot, with a high near 100.
Thursday Night
Mostly clear, with a low around 67.
Friday
Sunny and hot, with a high near 99.
