It will be the fifth snow day in a row, and seven days total for the school year. Columbia Public Schools had employees drive every route Thursday to determine if they were safe enough to re-open schools Friday.
"We have found many streets to still be completely snow packed," said CPS Superintendent Chris Belcher.
He said most of the problem streets are city neighborhoods and county roads.
ABC 17 News drove some of the routes. On Creasy Springs Road, the car was sliding and at one point even stuck.
Belcher said these are just not safe conditions for buses.
"I know people are going stir crazy and having cabin fever from being inside, but we cannot make a decision that puts kids in harm's way because we think we need kids back in school," he said.
Belcher said the roads were not the only factor that played into their decision.
"The thing that causes my greatest concern though is that it's going to be -6 degrees tonight, and if we have buses that go into the ditch or delayed while kids are waiting for the bus, that's dangerous," he said.
Because CPS has used all its built-in snow days, school will now go until June 5.
"If we miss the 7th day, that takes you to June 5th," he said. "But if you miss an 8th day, that's still June 5th. If you miss a 9th day, that pushes you to June 6th."
Belcher said for any snow days after the six built-in days, one day is made up for every two missed.
He also said in the past, the state hasn't required the district to make up any days after 10 snow days are used.
Belcher told ABC 17 News the decision to close school tomorrow is one he doesn't regret.
"When you're responsible for 18,000 students, I don't think there's a person in the community that, put in my chair, would make a different decision," he said.