Heat will soar to record levels across part of the northwestern United States from Thursday into the weekend.
"While temperatures have been above normal for the past several days in the Pacific Northwest, the heat will become more intense heading into the weekend," according to AccuWeather Meteorologist Ryan Adamson.
A seesaw temperature pattern will set up across the northern tier of the country, with temperatures climbing across the Pacific Northwest and taking a tumble farther east.
The clock-wise flow around a building high pressure system will send temperatures soaring past the century mark in some places.
"The heat will peak on Friday and Saturday," Adamson said, as a northeasterly breeze will allow the air to warm as it moves down the slopes of the Cascades.
Highs are expected to soar into the 100s from Medford to Portland, Oregon, with low 90s expected farther north in Seattle.
Even areas along the Washington and Oregon coasts, which are typically kept cool by the Pacific Ocean influence, will reach the low to mid-80s.
Daytime temperatures will generally range between 10 and 15 degrees Fahrenheit above average across the region. Some locations will creep close to 20 degrees above normal.
Medford and Seattle may surpass records that have held since the 1960s.
While temperatures will throttle back a bit on Sunday, especially near the coast, "record-tying or record-breaking heat is still likely," Adamson said.
"The intensity and duration of the heat will be especially difficult for those without air conditioning."
Those with outside commitments should take frequent breaks in the shade, drink plenty of water and wear light-colored and loose-fitting clothing during the heat of the day.
The area of high pressure, and consequently the heat, will begin to break down early next week.
"Temperatures should finally return to near normal by Monday," Adamson said.