The polar vortex that kept northern Illinois cold last week may come back.

NIU meteorologist Gilbert Sebenste said the polar vortex is a low-pressure system that occurs in northern Canada and is an annual phenomenon. Normally, the vortex doesn’t have such a drastic effect as it did in the U.S. last week, when temperatures fell below zero.

“[The polar vortex] came south this year for about three days — that was early last week — bringing with it cold air from Arctic area, which is why it got so cold,” Sebenste said. “It hasn’t moved this far south, though, in 18 years. It used to [come down] a lot more often, but now it’s rare.”

Sebenste said this may not be the last the Midwest sees of the polar vortex this winter.

“There is a chance that the polar vortex may move down again in about seven to 10 days. We’re closely watching that because that can be as bad as last time,” Sebenste said.

Sebenste said the average amount of local snowfall is 33 inches. So far 23 inches have fallen, so students should be prepared for more snow.

According to the National Weather Service, this week the DeKalb area will see temperatures from the mid-30s down to the low teens with snow.

With the possibility of more harsh weather, students have their own tricks to deal with the cold.

“In this kind of weather, I find it best to wear two pairs of socks, boots, hoodie and a winter coat,” said junior engineering major Christopher Frank.

As an alternative to being exposed to the cold by walking, students can ride a Huskie bus to class.

“Safety is important to Huskie Line, but the winter weather can make things very difficult for riders,” said Joseph Frascello, Student Association director of Mass Transit.

Frascello said students should plan to take an early bus route to make sure they are on time for class. Students should make themselves visible to the traffic, especially bus drivers.

Also important, Frascello said, is that students “be cool,” expect delays and prepare a back-up plan for local transportation.