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Over the days of 25 June - 29 June 2021, there was extreme heat in western North America

The US states of Washington and Oregon , as well as the Canadian Province of British Columbia , all achieved all time record maximum temperatures .
- in some cases more than 8C higher than any previously recorded temperature at the site.  An unofficial list of all the new all time record maximum temperatures in this event, courtesy of the "coolwx" website run by Dr. Robert Hart of Florida State University, is shown later on this page.

Below is a commentary on this event. Many of the charts, below, come from a US list-serve.

COMMENTS ON LARGE SCALE FEATURES

This first image, provided by Dr Paul Roundy at the University of Albany, shows was what the early predictors were for this event.

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Other models shared this early prediction of the event. Dr Cliff Mass, at the University of Washington, shared these plots from Dr Alicia Bentley (NOAA) web site. They show the GFS ensemble standardized anomalies, for which height anomalies were in excess of 3 standard deviations above normal for the location in question:

Some discussion that took place prior to the event. From Paul Wolyn:
"The GFS and EC have southeast flow at 850mb over the OR and WA.  Could the southeast flow advect the heating from the elevated mixed layer over central Oregon into the PDX and maybe the SEA area?  Much of central Oregon is at 4000 to 5000 feet MSL.  I wonder if this could be contributing to the extreme temperatures in the model runs.  It could be the "perfect" combination of many factors leading to the extreme heat."

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An unofficial list of all the new all time record maximum temperatures in this event, courtesy of the "coolwx" website run by Dr. Robert Hart of Florida State University. Some of the new all time record temperatures are more than 8C greater than the previously highest temperature ever recorded at the sites.

Many all time records were set. Additionally, the temperatures were substantially warmer than what is normal for these locations. Below shows the high temperature in Portland, Oregon, being 36 degrees F (20C) above normal.
Image Added

SOCIETAL IMPACTS

WA, OR, and BC are all usually cool and cloudy. Houses are built with large, south facing windows, to maximize sunlight into houses. Less than half of houses have air conditioning.  In short: WA, OR, and BC houses are all built to the past climatology of the area, and the heat they got was very far from that climatology. One approach taken was to board up windows. In contrast to an incoming tropical cyclone, in which the boarding up is to prevent glass from breaking, here, it was to block out the sun and try to keep in the cool air. Dale Durran, University of Washington: "One thing I did to prepare for the heat was buy some 4’x8’ sheets of 1/4” foam core and use them to block the direct sunlight in several windows.  Below is a photo of one row of such blocked windows.  I’m going to save these for really cold days too — they have to have an R value above most window coverings and work particularly well on the sloped glass."

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#4 - This was a high impact event. Temperatures were 20-25C above normal, in summer. The locations impacted were not built for this heat. As the climate of the earth changes, more events like this - where the weather is something never before experienced, and not something a community is prepared for - will likely happen.