A dangerous American heat wave is looming over the 4th of July holidays, the World Cup and a quickie wedding.

America’s northern neighbor Canada is also seeing extreme heat this week, with temperatures as high as 99F in Ontario.

Those high temperatures forced organizers to cancel a public World Cup viewing party for the Portugal vs. Croatia match in Toronto.

Heat warnings are also in place for much of Quebec, including Montreal and Quebec City.

High humidity will make conditions even more oppressive, with temperatures forecast to reach 115F in the coming days. The heat index is the feeling of the human body when the temperature is combined with the air temperature.

The heat is a persistent area of ​​high pressure over the central and eastern United States – also known as the “heat dome”.

As well as strong sunlight, dry soil is intensifying the heat – the northeast of the coast was in a drought this year. Without the release of soil moisture, the sun’s energy goes completely to baking the ground, thereby increasing the temperature.

Because of human-induced climate change, heat waves have become more frequent, more intense, and longer. The world has warmed by about 1.1C since the start of the industrial age and temperatures will continue to rise unless global governments make drastic cuts in emissions.

Temperatures in the Northeast will drop two degrees on July 4 with the threat of severe thunderstorms. Temperatures will still be well above average on Sunday and Monday as cooler air moves down from the north.