Extreme heat has forced the temporary closure of the Great American State Fair on the National Mall, among a series of events marking the July Fourth holiday in Washington, DC.

"The safety and well-being of our guests, volunteers, performers, vendors, and staff is our highest priority," the event organisers said.

More than 165 million people were sweltering on Friday under record temperatures along the US East Coast and Midwest, according to the US National Weather Service.

The heatwave is disrupting the holiday weekend as President Donald Trump hosts a celebration marking America's 250th birthday and multiple World Cup matches taking place outdoors.

The State Fair will reopen at 17:00 local time (22:00 BST) when heat conditions improve, the organiser, Freedom 250, said.

This extreme heat event, with temperatures soaring to 104F (40C) in places like Philadelphia and 103F in Washington, DC, is testing the limits of outdoor celebrations during one of America's most important holidays. The National Mall, usually bustling with festivities, has become a dangerous place for large crowds, with DC Fire and EMS treating multiple heat-related illnesses.

The broader pattern of record heat across the East Coast and Midwest, combined with the risk of severe thunderstorms, highlights the increasing frequency and intensity of extreme weather driven by climate change. As the world has warmed by about 1.1C since the industrial era, such events are becoming more common, longer-lasting, and more dangerous.

For organizers, the challenge is balancing tradition with safety. President Trump’s planned outdoor speech and the 4th of July fireworks show are proceeding with adjusted schedules, but the heat is forcing many communities to scale back or cancel events.

As cooler air is expected to arrive later in the weekend, the focus remains on protecting public health during this unprecedented early summer heat spell.