Six months after school started on a 98-degree day, the Denver school district is exploring having an alternative school calendar for its 55 schools without air conditioning.

Schools in Denver are set to begin for the 2020-21 year on Aug. 17 and end May 28. Superintendent Susana Cordova said the alternative calendar would start later and end later. The specific dates are still being worked out, she said.

“We know there are times when very high temperatures in the first weeks of school have resulted in hot classrooms,” Cordova said. “In an effort to mitigate the heat, we are exploring the possibility of offering an alternative calendar.”

The district’s next step, she said, is to survey staff at the 55 schools without air conditioning to see if they’re interested in using an alternative calendar.

Heat concerns lit up social media this past August, and teachers called on the district to act.

“I joke that I don’t teach reptiles, I teach mammals,” Lisa Yemma, a teacher at Slavens K-8 School, said in August. “Thirty middle schoolers in a room, it’s hot.”

In the last decade, Denver voters have approved nearly $90 million in tax increases to pay for heat mitigation in schools, including air conditioning. It would cost another $200 million to install air conditioning in the remaining Denver schools without it, district officials said in August.

Many Denver schools already set earlier start dates and make other calendar modifications. However, most summer child care providers don’t run their programs past the main district start date.