For many high school seniors, the massive storm that struck the East Coast on Monday not only raised the possibility of days without transportation, classes or electrical power; it also threatened to wreak havoc with their college applications.

The reason for students’ fears: Thursday marks a key annual deadline for many colleges to accept early applications. Authorities in northeast and mid-Atlantic states expect millions of people to be without power this week in the wake of Hurricane Sandy, making it extremely difficult for some students to meet the Nov. 1 target without the use of computers or Internet access.

As a result, several colleges announced Monday that they would push back their deadlines.

The University of Virginia said it would accept applications for early-action admissions through 11:59 p.m. Sunday. Early action is a program that allows students to secure an early-admission offer — in U-Va.’s case by January — without being required to make a decision until later in the school year. Last year, about 11,700 applicants sought early action at U-Va. Of those, about 3,200 were admitted and about 1,500 enrolled, said Greg W. Roberts, dean of admission at U-Va. Those students made up about two-fifths of the entering class.

With Sandy wreaking havoc on the Eastern Seaboard, Roberts said U-Va. wanted to give families more time “if in fact this is going to be as devastating to some areas as some people think.”

At the University of Maryland, which gives priority to applications submitted by Nov. 1, officials announced that the deadline would be extended, but they did not set a new one.

“We will, of course, work with prospective students and our school counselor colleagues to be as flexible as possible in helping them to complete the admission process,” Barbara Gill, U-Md.’s assistant vice president for undergraduate admissions and enrollment planning, said in an e-mail.

Johns Hopkins University extended its deadline for early-decision applications, which had been Thursday. Early decision, unlike nonbinding early-action programs, requires students to enroll if admitted. Johns Hopkins has not set a new deadline but will as soon as officials assess the storm’s impact.

“Students have a lot of anxiety about applications,” said David Phillips, vice provost for admissions and financial aid at Johns Hopkins. “The more you give them an extended deadline, the more they may pore over [an application], and edit it and re-edit. We don’t want students agonizing too much about it. We want to close the loop.”

At Washington and Lee University, which also has an early-decision program, officials said they would be flexible. “We’re asking them to get us their materials as soon as possible and to do their best to submit what they can before any possible power-related interruptions to Internet service,” said Jonathan Webster, associate dean of admission at Washington and Lee.

Similar deadline extensions were expected at many other schools.

Georgetown University officials plan to announce that their early-action application deadline will be bumped to Monday for those in storm-affected areas, a spokeswoman said.

College admission counselors said that Nov. 1 is perennially one of the biggest days on the application calendar. The days leading up to that deadline are some of the most stressful.

“I always encourage kids to work ahead of time,” said Bruce Vinik, an education consultant in Montgomery County. “You never know if something’s going to come up at the end that somehow throws a wrench into the process. This is a great example of why kids need to work ahead.”

Nina Marks, another Montgomery-based education consultant, said the storm could disproportionately affect applicants who have modest means. Those who are rushing to complete their applications, she said, often have fewer resources at home. For that reason, she said, it is crucial to extend the application deadline for students who may be affected by Sandy. “It’s one of the most urgent moments of the year,” Marks said.