Trump says he will still speak in Washington, DC, after a thunderstorm delayed celebrations in the US capital.

Severe weather has disrupted celebrations of the United States’ 250th anniversary of independence, including in Washington, DC, where a thunderstorm delayed a speech from President Donald Trump.

Thousands of people gathered in the US capital for the July 4th celebration on Saturday, but were then evacuated from the National Mall as the storm closed in.

But the group organising the event, Freedom 250, said they would be readmitted, and Trump would speak at 11pm local time (03:00 GMT), one hour⁠ later than previously scheduled.

“I will be there no matter what,” Trump posted on social media. “It’s Saturday night, LETS HAVE SOME FUN, even if we are out late tonight.”

In New York City, authorities put on a large fireworks display to mark July 4th celebrations, bringing the 30-minute show forward because of the threat of storms.

The rain and lightning stayed away, allowing thousands of people to enjoy the spectacle.

Elsewhere, severe weather prompted the cancellation of celebrations in Hartford, Connecticut, along with Harrisburg and Wilkes-Barre, Pennsylvania. Spectators at Boston’s fireworks and concert were told to briefly seek shelter before events later resumed.

An evacuation was also ordered in Philadelphia. Pittsburgh moved forward with fireworks but shifted the time to accommodate the shifting weather.

In Washington, DC, crowds were building at the National Mall several hours before the evacuation. Visitors contended with stepped-up security and temperatures that reached 39 degrees Celsius (102 degrees Fahrenheit) to get into the event.

The record-breaking heat wave forced the cancellation of several parades and other events in the area.

“It’s just part of the deal I signed up for,” said Glen Solander, 60, ‌a software engineer visiting from Sioux Falls, South Dakota, as he waited at a security checkpoint on Saturday afternoon.

Other visitors included the white nationalist organisation Patriot Front.

The group posted on social media that it had arrived in the capital, and hundreds of people wearing the group’s outfits travelled to the city on Metro trains serving the District of Columbia region.

Local police said they had not received any reports of violence.

Past presidents have generally avoided in-person appearances at July 4 celebrations, but Trump has blurred the line between official commemoration and campaign-style politics.

The Trump administration’s Freedom 250 group has largely sidelined a nonpartisan body set up in 2016 to handle the 250th anniversary ⁠and has fenced off much of the 2.4-kilometre (1.5-mile) National Mall for a “Great American State Fair” featuring attractions such ⁠as a Ferris wheel alongside displays by conservative groups and defence contractors.

Freedom 250 says the fair aims to showcase the people and innovations that make the US “the greatest nation on Earth”.

Several Democratic-led states declined to send delegations, and many performers scheduled to appear dropped out, citing concerns about partisanship.

Trump opened the event with a rally on June 24.

Other activities with Freedom 250 branding include a ⁠faith rally featuring mostly conservative Christian speakers, and multiple sports events, including a card of mixed martial arts bouts on the White House grounds for Trump’s 80th birthday on June 14.

An IndyCar race in Washington is scheduled for August.

The Freedom 250 organisation also sponsored “Freedom Trucks” that critics say paint an overly religious version of American history and gloss over issues such ‌as slavery and racial injustice.

Trump has sought to remake wide swaths of the capital city ahead of the 250th celebration, with mixed ‌results. ‌Many fountains and statues have been renovated, but problems have beset a much-touted $15m renovation of the Lincoln Memorial’s Reflecting Pool.

Security cameras and soldiers now stand watch over its peeling paint and algae-fouled waters.