After former President Donald J. Trump sat in a courtroom in New York for much of the last week, Saturday night was supposed to herald a return to the campaign trail and the large rallies where he often gives long, freewheeling speeches.

With thousands gathered on the tarmac at an airport in Wilmington, N.C., Mr. Trump’s campaign was building anticipation. Two hours before he was set to speak, the campaign sent a fund-raising blast with a message from Mr. Trump: “They can’t keep me off stage! Did they think I would run and hide?”

Ninety minutes later, the skies darkened to charcoal and lightning flashed. As thunderstorms swept toward the area and the National Weather Service issued watches and warnings concerning dangerous winds and hail, the rally was canceled over safety concerns.

“We’ll make up for this very quickly at another time,” Mr. Trump said on a call he made into the rally that was broadcast over the speakers. “We’ll do it as quick as possible. I’m devastated that this could happen.”

But the cancellation, which Mr. Trump indicated was out of his hands, highlights the challenges that he may face as he tries to balance his presidential campaign with a criminal trial that will keep him busy through May.

For much of the last week, Mr. Trump’s public comments had been limited to social media posts and remarks to reporters outside the courtroom. His only campaign stop was at a bodega in New York City, in a state he overwhelmingly lost in the last two elections and that is not expected to be in play in November.

Saturday’s rally was expected to serve as a preview of the upcoming weeks, with Mr. Trump traveling on weekends to campaign in battleground states that are more central to his efforts to return to the White House.

He has repeatedly claimed that the trial is preventing him from campaigning in places like North Carolina, which he won in 2016 and 2020, but where Democrats are making a big push in November. Opening arguments are slated to start on Monday, and the trial is set to last six to eight weeks.

As is often the case with Mr. Trump’s rallies, the crowds began lining up hours ahead of his expected remarks. Among those gathered outside was a group wearing shirts with the logo of the Proud Boys, a prominent far-right extremist group. One person held a sign that read “Free All of the J6 Prisoners,” a reference to those serving sentences in connection with the Jan. 6, 2021, riot at the Capitol.

Mr. Trump, who faces four criminal indictments that include charges tied to his efforts to overturn his election loss, has recently embraced dozens of Jan. 6 defendants. He has called them “hostages” and has said he would consider pardoning them.

In a statement, Ammar Moussa, a spokesman for the Biden campaign, criticized the group’s presence, pointing to remarks Mr. Trump made in a debate in 2020, in which he told the Proud Boys to “stand back and stand by.”

“This is Donald Trump’s America: where white nationalists and violent far-right extremists are empowered and working families are left behind,” Mr. Moussa wrote.

Chris LaCivita, a senior adviser to the Trump campaign, responded in a statement, “We don’t comment on stupid.”

Mr. Trump’s remarks were expected to face particular scrutiny given that he is under a gag order in his criminal trial that bans him from attacking witnesses, prosecutors, jurors and court staff, as well as their relatives and relatives of the judge. Prosecutors have said Mr. Trump has violated the gag order seven times, and there is a hearing about the issue on Tuesday.

Mr. Trump did travel to North Carolina earlier in the day, attending a fund-raiser in Charlotte in the afternoon. When he called into the rally, he told the attendees that he was minutes away from “flying in” to Wilmington but that the authorities “would prefer that we not come in” over safety concerns.

“I’m so sorry,” Mr. Trump said. “But we’ll do it again, and we’ll do it bigger and better. You have my promise.”

As the crowd left to seek shelter in their cars, vendors outside were still selling an array of merchandise, some of which had been created specifically for the occasion. One T-shirt promoted what it called the Wilmington stop on Mr. Trump’s “Save America” tour.

“I was there!” The shirt read. “Where were you???”

Robert Draper contributed reporting.