The West Milford School District has changed course and now will require mask wearing at the start of the upcoming school year.

The district originally announced that masks would be optional because of the extreme heat. But parents started a petition in protest, saying that they didn’t want their children to lose time in class because of COVID-19.

The school superintendent said that the mask policy would be enforced because the temperatures inside the schools isn’t hot enough to warrant the exemption.

The Toms River and Lacey Township school districts have made masks optional because of the heat.

Gov. Phil Murphy announced earlier this summer that students, staff and facility would be required to wear masks in school. There is an exemption for when it gets too hot.

But it is unclear how hot is too hot. State Health Commissioner Judith Persichilli said that parents should trust teachers and administrators to make that determination.

“We do know that kids become very uncomfortable, as we all do, with masks on when it’s really hot and humid. We’re just going to have to trust that the teachers make the right decision for their students, and keep kids physically distant from one another,” Persichilli said on Wednesday.

The commissioner said that more than half of kids 12 to 17 years old have received at least one dose of the vaccine. That number rises to two-thirds among 16- and 17-year-olds.