Western Washington is braced for unusually hot weather this week, but University of Washington scientists say this could be one for the record books, with Seattle experiencing historic triple-digit readings.

The UW Probability Forecast shows a Wednesday high temperature of 102 degrees in SeaTac, site of Seattle-Tacoma International Airport, where the official Seattle temperature is recorded. The all-time record high for Seattle is 100 degrees, set July 16, 1941, in downtown Seattle and tied July 20, 1994, at Sea-Tac airport. The probability forecast says the temperature could reach as high as 107 in SeaTac, but also could top out at 98.

In his weather blog, Cliff Mass, a UW atmospheric sciences professor, notes that the heat wave that began on Sunday could stretch into next weekend, though the temperatures should cool somewhat by Friday.

"We are about to enter an historic heat wave for our region," he wrote.

He also noted that Portland and the Willamette River Valley in Oregon are likely to be even warmer, with temperatures well into the 100s.

Already cooling centers have opened in several areas to help people beat the heat. Residents are being urged to check on elderly friends and neighbors, who could be particularly vulnerable, especially those who lack air conditioning.

Mass noted that heat waves are the most dangerous weather phenomenon in the world, and that many more people die from heat than from hurricanes, tornadoes and windstorms.

The UW Probability Forecast is designed to provide uncertainty information along with a probabilistic weather forecast. The Web site was developed at the UW Applied Physics Laboratory based on research conducted in the departments of atmospheric sciences, statistics and psychology.

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For more information, contact Mass at 206-685-0910 or cliff@atmos.washington.edu.