Publication Date August 3, 2017

Pacific Northwest threatened by hottest weather ever recorded; Seattle could hit 100

United States
European model simulation of heat dome over Pacific Northwest Thursday. Image:

Seattle has posted only three days in the triple digits in the last 123 years. The hottest temperature ever recorded in Seattle was set July 29, 2009, when the mercury reached 103 degrees.

“If Seattle hits triple digits on Thursday or Friday, it’ll be the third time in the past 23 years — after reaching it only once in the first 100 years of weather observations,” notes The Seattle Weather blog. It has never before hit 100 in August.


Already, Seattle logged its second warmest low temperature ever recorded Wednesday, only dropping to 69 degrees. Its high temperature was 91, which broke the Aug. 2 daily record of 89 set in 2009.


On Wednesday, despite smoke wafting through the city, Portland climbed to 103 degrees, shattering the Aug. 2 daily record of 96 set in 1986.

Statistics geek will find fascinating that the GFS model predicts temperatures near the surface in Portland to be seven standard deviations (7 sigma) from the mean Thursday. In plain English, this means that this is an incredibly rare and extreme heat situation.