President Donald Trump on Saturday delivered a Fourth of July address from the National Mall, praising the American spirit and the founders who fought the British 250 years ago to pave the path to American independence -- hours after the event was delayed by weather in the nation's capital.

Taking the stage at 11:15 p.m., an hour and 15 minutes after originally planned, the president said, "Tonight we pledge allegiance to the flag they gave us, and we say, God bless the immortal patriots of 1776. And long live the cause of independence."

The president brought up present-day politics. During the speech, he promoted his signature SAVE America Act, which would drastically change the administration of American elections just months out from the midterms, and repeatedly railed against communism.

Disney Celebrates America live updates

During his speech, Trump touted several historic flags that hung on the stage behind him, including an original 1777 flag and the flag that draped over President Abraham Lincoln's coffin. The president had multiple veterans and Medal of Honor recipients from various American wars come onto stage at several points to salute the historic flags.

The speech, which culminated in a flyover and a massive fireworks display, came following a major disruption to the show as crowds who waited for hours in the record heat were forced to evacuate the grounds due to thunderstorms hitting Washington, D.C.

The preliminary high temperature in Washington, D.C., Saturday was 102 degrees -- making it the hottest July Fourth on record for the city, according to ABC News' meteorologists. It broke the previous record high of 100 degrees set on July 4, 1919.

Severe storms roll through parts of US as heat wave continues

At times during the evacuation, there was confusion among the crowd as the dispersal orders were announced.

The president thanked the crowd for their patience.

"I want to thank everybody, because they did the right thing. They saw lightning. And I said, 'There's no way if we have to speak in front of one person at 4 in the morning, I'm going to be here.' There's no way we can be deterred," he said.

The "Salute to America 250 Celebration & Fireworks" celebration was slated to begin at 7 p.m. but did not start until 10:45 p.m.

Almost all of the musical guests and performances were cancelled due to the late start.

Trump remained determined to give his speech, which he vowed earlier in the week would happen despite the heat.

"One of my very brilliant people backstage said, 'Don't worry about it, sir. We can do it. Maybe next week.' I said, 'It doesn't work next week. This is the big day, we want July Fourth," he said.

Twelve people on the National Mall and surrounding area were transported to local area hospital because of the triple digit heat as of 8 p.m. Saturday, according to local authorities.

The president's speech came as he and his administration have faced pushback for controversial domestic and international policies. The president also faces low approval ratings -- though a June Quinnipiac poll found them up from the lowest of his second term.

1st confirmed descendants of enslaved person who helped build White House speak to ABC News

According to the poll, 38% of voters approve of Trump and 55% disapprove (in May it was 34% to 58%).

Quinnipiac found majorities of voters disapproved of the way that Trump is handling immigration issues, the economy, foreign policy and the ongoing war with Iran.

ABC News' Beatrice Peterson, Fritz Farrow, Noah Minnie, and Daniel Peck contributed to this report.