The bottom line: we are about to experience a historic regional heatwave, which will break both daily and all-time temperature records. &nb

Cliff Mass Weather Blog

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2021-06-23 22:30:04

The bottom line: we are about to experience a historic regional heatwave, which will break both daily and all-time temperature records.

A heatwave that is made even more unusual by its timing, occurring far earlier than most of the major extreme-warmth periods of the past.

Before I provide the torrid forecast--and tell you why I am confident in it-- let's review how warm things have gotten in our region in the past.

The all-time record high for Washington State, based on observations going back approximately 125 years, is 118F at Ice Harbor Dam near Pasco on August 5, 1961. In Oregon, the record high is 119F observed in Prineville and Pendleton, on July 29th and August 10th--both in 1898.

You will note that many of these record temperatures are well in the past. A plot of record temperatures I found on plantsmap.com, shows that eastern Washington has lots of record highs from 110-115F, while southwest WA has surged into 100-108F territory. Northwest WA is substantially cooler.

As I will describe below, I expect temperatures will approach and/or exceed these temperatures over the weekend and Monday, and there is an excellent chance that some all-time records will fall.