Scorching heat disrupts Fourth of July events across eastern US

A dangerous heatwave upended Fourth of July celebrations across swaths of the central and eastern US on Friday, forcing officials in the nation's capital and elsewhere to cancel or postpone dozens of parades, concerts and fireworks displays.

Among the events disrupted by the sweltering heat was the Great American State Fair on the Mall in Washington, a centrepiece of President Donald Trump's efforts to mark the nation's 250th birthday.

The fair was temporarily closed on Friday afternoon as temperatures reached 101 degrees Fahrenheit (38 degrees Celsius). Organisers said they expected it to reopen at 5 pm, with modifications like cooling tents and misting stations.

Record-breaking temperatures spread to the eastern US from the Midwest earlier this week due to the emergence of a high-pressure system known as a "heat dome," which traps a mass of hot air over a region and can cause humidity to spike.

Over 185 million people, more than half the US population, were under heat alerts on Friday, the Weather Service said. Peak heat indexes could reach 115 F (46 C) in parts of the country.

Forecasters and government officials have warned that the heatwave could prove deadly. They urged Americans celebrating the Fourth of July weekend outdoors to stay hydrated, seek shade and watch for signs of heat illness at gatherings and public events.

Event cancellations were reported across the Eastern Seaboard for the July 4 weekend, when Americans typically gather for barbecues, parades and fireworks displays to celebrate the nation's 1776 Declaration of Independence from Britain.

In Philadelphia, officials cancelled the Salute to Independence Parade, a marquee event in the city's semi-quincentennial celebrations, citing extreme heat. The decision came after temperatures hit 103 F on Thursday, tying a record high last seen in 1901.

Elsewhere, heat-related disruptions rippled across the region. Haddon Township, New Jersey, cancelled its annual July 4 parade, while Watertown in upstate New York called off its Independence Day concert and fireworks display. In Boston, officials delayed entry to an annual riverside fireworks celebration by four hours, to 4 p.m. instead of noon.

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