FORSYTH COUNTY — Temperatures fell to 10 degrees before dawn in Marietta, Cartersville and Rome and 12 in Atlanta as an arctic blast of frigid weather brought the coldest temperatures in a year to Georgia.

It was even colder in the north Georgia mountains. A U.S. Forest Service weather station recorded an air temperature of 0 degrees shortly after 5 a.m. Thursday at Brasstown Bald, Georgia's highest peak.

Some school districts across the state were delaying start times. However, that was not the case in Forsyth County, where the public school system proceeded with a normal schedule.

Officials huddled Wednesday to make a determination about Thursday. Ultimately, they decided to operate normally. Jennifer Caracciolo, spokeswoman for the district, said considerations included safety, facilities and transportation.

Whether pipes will freeze or have frozen, the ability to start buses on time and potential precipitation are factors, as is the general safety of children to be outside.

Officials did not discuss school closures for Friday. While it is not preferable to make the decision the day of, Caracciolo said, that’s “often when the weather changes.”

All decisions to delay or close school are made at the latest by 5:30 a.m.

If school is closed, online learning through the district’s new virtual system will not take effect until the third lost instructional day this year.

A wind-chill advisory Thursday morning included all of northern and central Georgia and parts of south Georgia, including Vidalia, Americus and Statesboro.

The wind chill — the combination of air temperature and wind — was 4 degrees below zero before dawn Thursday in the northwest Georgia town of Calhoun.