The heat wave was characterized as a heat dome because of the extreme temperatures and the exceptionally strong ridge centered over the area, whose probability of formation was linked to the effects of climate change by multiple studies. The record-high temperatures associated with the heat wave stretched from Oregon to northern Manitoba , and daily highs were set as far east as Labrador and as far southwest as Southern California.
The extreme heat sparked numerous, extensive wildfires, some reaching hundreds of square kilometers in area. The eponymous Lytton wildfire destroyed the village of Lytton, British Columbia , the day after the city set the record high temperature for Canada.
Extreme heat also damaged road and rail infrastructure, forced closures of businesses, disrupted cultural events, and melted snowcaps, in some cases resulting in flooding. The death toll has been estimated to exceed 1, people, with at least deaths estimated in western Canada. On June 23, the United States National Weather Service warned of an approaching heat wave in the Pacific Northwest, [ 17 ] whose origins could be traced to torrential rains in China.
When that air current encountered an upper-level high-pressure zone, also called a ridge, it started to significantly deform, being forced to accommodate the high-pressure area south of the jet stream's meander. These conditions made way for a massive Rex block. After the heat dome hovered over British Columbia and the Northwestern United States for a few days, it began to move eastward, bringing relief to the Pacific coast but breaking records east of the Rocky Mountains , particularly in the northern parts of the Prairie provinces.
Climate change in Canada and in the United States are widely considered to have worsened the heat wave's unprecedented intensity and duration. Broader climate shifts may have also contributed to worsening the heat wave; data provided by Verisk shows that the Pacific Northwest is among the fastest-heating regions in the continental United States and southern Canada. The highest temperatures of the heat wave were registered in British Columbia, but areas as far east as Ontario were affected by the event.
