WASHINGTON (Reuters) – A dangerous heatwave upended fourth of July celebrations across swaths of the central and eastern US, forcing officials in the nation’s capital and elsewhere to cancel or postpone dozens of parades, concerts and fireworks displays._x000D_
_x000D_
Among the events disrupted by the sweltering heat was the Great American State Fair on the National Mall in Washington, a centerpiece of President Donald Trump’s efforts to mark the nation’s 250th birthday._x000D_
_x000D_
The fair, designed to showcase all 50 states, was temporarily closed on Friday afternoon as temperatures reached 38 degrees Celsius._x000D_
_x000D_
Late on Friday, organisers of the National Park Service’s Independence Day Parade in Washington announced they had canceled the annual event due to safety concerns._x000D_
_x000D_
The parade had been scheduled to start on Saturday, with the Weather Service projecting heat index values to reach as high as 115 degrees Fahrenheit._x000D_
_x000D_
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._x000D_
_x000D_
The scorching conditions also strained power grids._x000D_
_x000D_
PJM, the largest US power grid operator serving 67 million people in the Mid-Atlantic, South and Washington, DC, areas, ordered customers enrolled in emergency conservation programs to curb usage._x000D_
_x000D_
The steps were needed to battle generator outages, overloaded transmission lines and a surge in air-conditioning demand due to the heat._x000D_
_x000D_
In New York, Con Edison said roughly 17,000 customers were without power as of late Friday afternoon._x000D_
_x000D_
As demand surged, it urged customers in New York City and Westchester County to conserve electricity._x000D_
_x000D_
In New York City, shoe soles stuck to Manhattan streets as adhesives softened in the heat._x000D_
_x000D_
The city’s extreme heat warning did not stop fans from gathering on sweltering sidewalks to watch celebrity guests arrive at Madison Square Garden for what was widely expected to be the wedding celebration of pop megastar Taylor Swift and football hero Travis Kelce._x000D_
_x000D_
A worker waved SUVs carrying guests into the venue while holding a water bottle in one hand and a towel to wipe sweat from his face in the other._x000D_
_x000D_
Over 185 million people, more than half the US population, were under heat alerts on Friday, the National Weather Service said._x000D_
_x000D_
Peak heat indexes could reach 46°C in parts of the country, with several cities setting record temperature highs._x000D_
_x000D_
Forecasters and government officials have warned that the heatwave could prove deadly._x000D_
_x000D_
They urged Americans spending the long weekend outdoors to stay hydrated, seek shade and watch for signs of heat illness at gatherings and public events._x000D_
_x000D_
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._x000D_
_x000D_
In Philadelphia, officials cancelled the Salute to Independence Parade, a marquee event in the city’s celebrations, citing extreme heat._x000D_
_x000D_
The decision came after temperatures hit 103 Fahrenheit on Thursday, tying a record high last seen in 1901._x000D_
_x000D_
Elsewhere, heat-related disruptions rippled across the region. Haddon Township, New Jersey, canceled its annual July 4 parade._x000D_
_x000D_
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 4pm instead of noon.