Fox News Weather Center

Stifling heat to build into interior Northwest at midweek

Following a string of pleasantly warm days, residents of the interior northwestern United States will be in for a period of oppressively hot weather.

At this time of year, high temperatures usually top out near 70 F in the lee of the northern Cascades and throughout Idaho and western Montana and Wyoming. Since this past weekend, thermometers have been surpassing these numbers.

However, even more intense heat is on the way as the jet stream - a river of fast-moving air high up in the atmosphere - moves to the north of the region.

This will keep sunshine and warm southerly winds flowing, pushing desert heat northward unobstructed.

As a result, afternoon temperatures will surge to levels 10- to 20-degrees Fahrenheit above average in the interior Northwest beginning on Wednesday.

NW heat 6/5

The normal high of 70 F in Great Falls, Montana, will be surpassed by the late morning on Wednesday, before reaching the mid-80s that afternoon and challenging the 90-degree mark on Thursday.

A Pacific storm crashing into the coast on Thursday will push the most stifling heat inland across Montana.

“It will be much more comfortable Thursday with temperatures 10 to 15 degrees lower compared to Wednesday,” said Doll.

Temperatures will still peak at well above-average levels before the unsettled weather arrives.

Despite an average high in the upper 70s, temperatures in Salt Lake City will soar into the 90s each day through the end of the week, virtually unaffected by the incoming storm.

“If it’s necessary to be outside for a prolonged period of time in the afternoon, people should drink plenty of water to keep properly hydrated,” said Doll.

“Pets should not be left outside for long periods of time as the heat can be dangerous for them as well.”

Despite the oppressive heat and glaring sunshine, residents should avoid taking a dip in area streams and rivers.

Cold water shock and hypothermia are dangers associated with swimming in these waters. The latter can occur in any water temperature below 70 F, according to the Centers for Disease Control and Prevention.

Along the Pacific Coast of Washington and Oregon, the nearby influence of the cool ocean will limit rising temperatures.