Fox News Weather Center

Northwestern US heat wave to jeopardize all-time record highs at midweek

Dangerous heat will build across the western United States, putting all-time record highs in jeopardy across the I-5 corridor of the Northwest at midweek.

“An abnormally strong ridge of high pressure will bring record-shattering heat to the Pacific Northwest,” AccuWeather Senior Meteorologist Dan Pydynowski said.

The heat dome will build over the majority of the West from California to Washington, Idaho and British Columbia.

Temperatures will climb 5 to 15 degrees Fahrenheit above normal with multiple days in the 100s from Fresno and Redding, California, to Reno, Nevada; Boise, Idaho; and Pendleton, Oregon.

NW heat begins July 30

However, communities west of the Cascade Mountains will endure the greatest departures from normal.

“The heat will peak at midweek, around Wednesday and Thursday,” Pydynowski said.

Daily record highs will be shattered these days as triple digit-heat is expected to engulf most of the I-5 corridor in Washington and Oregon.

More typical highs as July transitions to August range from the upper 70s in Seattle to the lower 80s in Portland, Oregon, to the lower 90s in Medford, Oregon.

“Medford may break its daily record high by around 10 degrees on Wednesday,” Pydynowski said.

Medford will join Portland and other communities in flirting with an all-time record high on Wednesday and Thursday. This corridor should also turn hotter than Phoenix these days. Monsoonal thunderstorms and clouds will keep temperatures in check across the Desert Southwest.

“During the extreme heat wave, people should wear light-colored clothing, stay well-hydrated with water and try to limit time outdoors to the mornings and evenings,” Pydynowski said.

“If you have to be outside during the day, take as many breaks as possible in the shade or indoors in air conditioning.”

Residents without air conditioning will want to crank up fans or seek cooling in a basement or local shopping center. Be sure to check in on the elderly without air conditioning to make sure they are following these precautions.

The increased energy usage could lead to power blackouts.

As sizzling sunshine sends temperatures soaring, remember to never leave children or pets locked in a car even for a short amount of time.

Residents should also use care with cigarette butts or campfires as an elevated fire danger will accompany the extreme heat.

Those looking to beat the heat can head to the cooler mountains or the immediate coast. However, an offshore flow may be enough to minimize the cooling effect from the ocean and cause temperatures to still soar along the Washington coast on Thursday.

It will take until next weekend approaches for the heat to finally release its grip on the Northwest.

“The ridge should begin to weaken heading into Friday and Saturday,” Pydynowski said. “So while it will still be very warm with above-normal temperatures, the record-breaking heat should come to an end.”