The National Weather Service office in Missoula is predicting that Western Montana Fair week will be brutally hot, with temperatures nearing the triple digits by the end of the week.

Meteorologist Leanne Allegretto said a massive high pressure system has parked itself over the entire western part of the United States, and it shows no sign of moving.

“By the middle to the end of the week we will probably see our first 100 degree day here in Missoula and the Bitterroot,” said Allegretto. “It’s going to be at least in the upper 90’s starting on Tuesday and just going up from there.”

Allegretto described the pattern that will keep temperatures hot for the near future.

“There’s a very high amplitude ridge of high pressure over the entire western United States, and with the stable hot flow over us, the temperatures are going to keep warming,” she said. “There’s not much in the way of any cold fronts moving in, so the temperatures will just keep on bumping up two or three degrees every single day.”

Allegretto said this high pressure pattern will not be accompanied by any later afternoon or even thunderstorms to provide some relief from the heat.

“We actually do not have any thunderstorms in the forecast,” she said. “Whenever we do have afternoon thunderstorms, it’s typically monsoonal moisture coming up from the desert southwest, but we don’t have that this go around, so right now, we’re just looking at hot and dry.”

Mercifully, Allegretto said the 100 degree days will only last Thursday into Friday. A weak system will come through for the weekend providing some relief from the heat, but it will not contain any moisture.