On the stifling first day of school, Jane McDougal’s second-grader and his classmates in Prince George’s County found no relief in the classroom. Their window air-conditioning unit was broken, she said, and there was no cool spot to relocate.

“It was pretty uncomfortable,” said McDougal, a mother of three and president of her school’s Parent-Teacher Association. But after her Maryland school system announced it would send students home early the second day of the school year — Wednesday — because of such problems, she had new concerns.

“We’re going to lose too much class time,” she said, noting that hot days are not unheard of in the region. “Making sure we have functional air-conditioning would be much better. They can’t possibly shut down early every time it’s going to be hot.”

Temperatures again surged above 90 degrees across the Washington region Wednesday, and Maryland’s second-largest school system was forced to send more than 134,000 students home early because of the hot weather and concerns that its aging air-conditioners weren’t up to the task of keeping students and teachers cool.

Over 40 of more than 200 public schools in Prince George’s reported air-conditioning problems this week — evidence of long-standing repair needs in a system with schools that are, on average, nearly a half-century old. District officials said they opted to dismiss students two hours early Wednesday to ensure student safety during what are typically the hottest hours.

“This was really a precaution for students and staff,” said Christian Rhodes, the system’s chief of staff.

Many in the community said they did not recall another time in recent years when students were dismissed districtwide because of hot weather and air-conditioning issues. And as they debated the decision and its causes, it also emerged as a flash point in the governor’s race.

School system officials said repair crews worked late into the night Tuesday and started again before dawn Wednesday to resolve problems. Many issues were relatively minor, but 12 schools had larger problems with chillers or compressors, they said.

All schools were slated to be open for a full day of classes Thursday. A district spokeswoman said the air-conditioning problem at the school of McDougal’s son, Kenilworth Elementary, was fixed.

In some cases, principals and staff moved classes from warm rooms to cooler ones, officials said. But the issue is aging infrastructure, Rhodes said. All Prince George’s schools are air-conditioned, with central systems or window units.

The county’s schools have about $2 billion in unmet maintenance needs, he said, and $8 billion more is needed for school modernization and construction over the next 20 years.

“Unless we figure out how to finance that, we’re always going to be dealing with old buildings,” he said. Fixing an air-conditioning system, he said, “is really just a Band-Aid to a much larger issue.”

Some parents, educators and elected officials said they understood the funding problems while others said the episode suggests a lack of preparation for the school year.

In the drive-through lane outside Eleanor Roosevelt High School in Greenbelt, Sam Gupta, father of an 11th-grader, hesitated before cracking his car window and letting precious air conditioning escape.

He acknowledged the day was sweltering but said the school system should have ironed out cooling issues over the summer.

“It shouldn’t be closed,” said Gupta, a 48-year-old Greenbelt resident and restaurant manager.

The day before, his daughter complained to him about the heat in the school’s temporary classrooms. There was no air-conditioning, he said — just a small fan. Parents should not have to send their kids to schools that aren’t equipped to handle extreme temperatures, Gupta said.

Ian Gleason, a sixth-grade teacher at Charles Carroll Middle School in New Carrollton, said the school system should be strategic in choosing which schools it closes, so that those without problems stay open. He understands the system has limited resources, he said. “It’s hard to have perfect equipment everywhere,” he said.

District officials said the complexity of bus routes makes it difficult to close just some schools early and not others.

School board member David Murray (District 1), a member of the minority bloc, pointed out hot weather is hardly unusual in the region.

“Even though it’s clearly warm, I think it could have been anticipated,” he said. “We see other school systems around us that are better prepared for this and are not closing.”

He said he did not regard the early dismissals as a proactive measure.

“This is the opposite of proactive,” he said. “This is reactive.”

School system officials said they had prepared for the first day of school.

“It wasn’t as if we were asleep at the wheel,” said Rhodes, the chief of staff. “It was a perfect storm. We had extremely high temperatures, we had staff and students coming to school, which increased the temperature inside buildings, and we have aging infrastructure.”

In neighboring Montgomery County, one school dismissed early Tuesday, but none did Wednesday. County officials said three schools reported problems Wednesday, but all were addressed before 10:50 a.m.

Montgomery schools spokesman Derek Turner said the district’s repair crews have been busy the past week, tending to issues at 27 schools. All were resolved.

In the District, Seaton Elementary in the Shaw neighborhood dismissed students early Wednesday when the air conditioning malfunctioned. The principal said the air conditioning was working again by the afternoon and that classes would resume Thursday.

In Virginia’s Prince William County, outdoor extracurricular activities at some schools, including football practice, have been canceled during the past week and a half, according to the school system. In Loudoun County, athletic practices were moved inside because of the heat.

Parent Llew Brown, a father of three and Parent Teacher Student Organization leader in Bowie, had a hint of the problems to come last Friday, when he attended his ninth-grade son’s orientation session in a Bowie High School gym. “I was perspiring at 8 a.m.,” he said.

Brown said he and other community members need to hold decision-makers accountable for the efficiency of the system. But he noted other issues, too.

“It comes down to needing fair funding for our schools,” he said. “The teachers and administrators are doing the best they can with the resources they have.”

Perry Stein and Debbie Truong contributed to this report.