CHARLOTTE, N.C. -- The burst of cold weather Charlotte residents woke up to Tuesday impacted thousands of students and teachers returning to class after winter break.

Nearly a dozen districts around the Charlotte area operated on a delay. In part, the delays were so kids did not have to stand in the cold while waiting for their school bus.

However, the buses were also to blame.

Mechanic Jimmy Hampton said the buses in the south react differently to freezing temperatures due to their engine type.

"Diesel is more temperamental to the cold," Hampton said. "The fuel will gel when its gets cold... the Glo plugs, if they aren't working properly, make it so it won't even start."

Parents are being encouraged to help their kids replace "looking cool" with being warm.

Doctors say children of all ages need to be kept warm regardless of the temptation to leave the house in just a hoodie.

"Older children and adolescents do tend to push the limits and sometimes parents feel that they need to give in to that," Cleveland Children's Clinic Dr. Kimberly Giuliano said. "But it is really important for children of all ages to be kept warm below freezing temperatures, (the) risk of frostbite if our most significant concern."

For a list of current closures and delays, click here.