Was this the "world's most extreme heatwave in modern history?"

A couple of meteorologists think so. Meteorologist Bob Henson and former National Oceanic and Atmospheric Administration (NOAA) hurricane scientist Jeff Masters have said, "Never in the century-plus history of world weather observation have so many all-time heat records fallen by such a large margin than in the past week's historic heatwave in western North America." 

The deaths in British Columbia last week included 500 "sudden and unexpected" deaths, which are believed to be connected to the record temperatures that the region has suffered in recent days. Ninety percent of the small village of Lytton in British Columbia was destroyed by the fires that accompanied the heat wave, which reached 121 degrees on Tuesday.

And then NOAA said that 55 U.S. stations had the highest temperatures in their history in the week ending June 28; "More than 400 daily record highs were set. Over the past year, the nation has experienced about 38,000 daily record highs versus about 18,500 record lows, consistent with the 2:1 ratio of hot to cold records set in recent years."