The National Weather Service is now saying heat advisories are likely to remain in place for the entire week, as Western Montana comes directly in line with a massive high-pressure ridge that's already been setting weather records along the coast. 

Forecasters say the valleys of Western Montana will be in the upper 90s, to as warm as 105 degrees in some locations like the Lower Clark Fork and the Kootenai, before temperatures start to ease a little on Thursday. 

It will be worse in Central Idaho, where temperatures will reach as warm as 112 degrees. Locations east of the Divide will also be close to 100 degrees by mid-week. 

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Very Strong High Pressure

Forecasters along the coast have been saying this is one of the strongest high-pressure systems they've seen in July, and it's already broken records in many locations.

Up to now, the Northern Rockies and Inland Northwest have been spared the really hot afternoons, but that's changing as the high moves east. By Wednesday, even North Central Montana will warm into the upper 90s.

NWS advises residents to drink plenty of fluids, stay out of the sun if possible, check on relatives and neighbors, and if they have to be outside, hydrate and watch for signs of heat exhaustion. 

NWS graphic
NWS graphic

Winds and Fire Weather

So far, Montana has benefitted from a wet spring and start to summer with only periodic bursts of heat. But that's changing this week and we're expecting fire dangers to rise this week.

Thursday could bring a threat of "fire weather", with low humidities, and as the ridge flattens a bit, gusty west winds could develop, leading to "red flag" conditions.

Nothing but the heat in the extended forecast

The Climate Prediction Center continues to show a "high likelihood for well above normal temperatures" persisting through the weekend of July 20th.

There is a chance some monsoonal moisture could make its way into Central Idaho and Western Montana on Sunday and Monday. But it's still too early to forecast the amount of moisture and threat of thunderstorms.

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Gallery Credit: Chris Wolfe

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