Dangerous heatwave scorches US East Coast as fourth of July celebrations begin

Millions of people across the US East Coast are sweltering under record temperatures as the Fourth of July holiday weekend gets underway, with the extreme heat described as "extremely dangerous conditions" by New York City Mayor Zohran Mamdani.

Millions of people across the US East Coast are sweltering under record temperatures as the Fourth of July holiday weekend gets underway, with the extreme heat described as “extremely dangerous conditions” by New York City Mayor Zohran Mamdani. The heatwave, which will continue on Friday, represents the hottest spell of the year so far, sending mercury soaring to levels not seen in some areas for decades and potentially disrupting a busy weekend of celebrations.

On Thursday, New York City hit 100°F (38°C), its hottest day since 2012, and could reach triple digits again on Friday. Philadelphia recorded its highest temperature since 2011—103°F (39°C). The widespread nature of the event, affecting 25 million people across central and eastern areas, sets it apart as potentially dangerous, with searing heat and high humidity making conditions particularly hazardous. The Fourth of July holiday, traditionally characterized by outdoor activities such as barbecues, community parades, and fireworks, is now under threat from the extreme weather.

The heatwave could also disrupt President Donald Trump’s celebration marking America’s 250th birthday, as well as multiple World Cup matches taking place outdoors. In Canada, Hydro-Québec reported that at its peak, more than 137,000 customers in the province were without power, with outages caused primarily by strong wind and lightning. The extreme conditions follow an unprecedented spell of early summer heat across Europe, with record highs across the continent, and come as scientists warn that heatwaves have become more frequent, more intense, and longer-lasting because of human-induced climate change. The world has already warmed by about 1.1°C since the industrial era began, and temperatures will keep rising unless governments worldwide make steep cuts to emissions. Temperatures in the northeast are expected to drop slightly on July 4 with the threat of severe thunderstorms, but will remain well above average, with a more significant drop expected Sunday and Monday as cooler air moves down from the north.