TULSA, Oklahoma - It is back to school for students in several districts, including Tulsa Public Schools Thursday morning.

Bus drivers for Tulsa Public Schools got an early start Thursday at the school bus facility to make sure students will stay warm on their ride to school.

Tulsa Public Schools tells News On 6, drivers got to the bus facility earlier than usual Thursday due to the chilly temperatures.

The district says schools are all given a special chart, that outlines when it's comfortable for kids to be outside or when it's too dangerous.  Based on the Thursday's chilly temps and wind speeds, Thursday is considered a dangerous day.

The opening bell for Tulsa Public elementary school students is 7:30 a.m.  The high schools start a bit later at 8:30 a.m.