America’s northern neighbour, Canada, has also been seeing extreme heat this week, with temperatures up to 99F on the horizon in Ontario.
Heat warnings are also in place across much of Quebec, including Montreal and Quebec City.
Forecasters say high humidity levels will make conditions feel even more oppressive, with heat index values set to reach 115F in the coming days. The heat index is what the temperature feels like to the human body when relative humidity is combined with the air temperature.
The heat is building under a persistent area of high pressure in the central and eastern parts of the US – also known as a “heat dome”.
As well as strong sunshine, dry soil is intensifying the heat – the coastal Northeast has been in drought this year. Without soil moisture to evaporate, solar energy goes entirely into baking the ground, thereby amplifying temperatures.
Heatwaves have become more frequent, more intense, and last longer because of human-induced climate change. The world has already warmed by about 1.1C since the industrial era began and temperatures will keep rising unless governments around the world make steep cuts to emissions.
Temperatures in the Northeast will drop a couple of degrees on 4 July with the threat of severe thunderstorms. Temperatures will still be well above average, though with a more significant drop on Sunday and Monday as cooler air moves down from the north.
