Spring is a season of warmer weather, the return of rain and thunderstorms and sometimes, tornados.

Tornado season is March through June, but a tornado can happen at any time, said NIU staff meteorologist Gilbert Sebenste.

“Transitioning from winter to summer, a jet stream lies across our area,” Sebenste said. “As this happens, warm, moist air tries to push out the cool air. As cold air tries to stay in place and cool fronts come in, that warm air is lifted into the atmosphere. Those form thunderstorms, and the jet streams help those storms to rotate.”

Tornados happen most often in spring, Sebenste said.

“We actually don’t know what causes a tornado. The science is still on-going,” said geography assistant professor Walker Ashley.

The peak time for a tornado to form is 5 to 7 p.m., Ashley said.

Tornado warnings for the north and northeast come from the National Weather Service center in Romeoville.

The weather service watches for when these types of storms are trying to form, Sebenste said.

When a warning goes out, it does not necessarily mean a tornado is on its way, said Ken Labas, National Weather Service forecaster.

Reasons for tornado warnings vary, and are sometimes just a precaution.

“[It] may not be on the ground, and may never be,” Labas said.

If a person finds themselves driving during a tornado, one option is to drive the other direction, Labas said. If that is not an option, park, exit the car and get behind a fixed object, Labas said.

“Be aware of what’s going on,” Labas said.

If a warning goes out and you’re indoors, find the most interior place at the lowest point, like a bathroom or interior hallway, said Ashley. If caught outside, Ashley said to find your way into a building.

“The last resort is to lie in a ditch and cover your head,” Ashley said, “The worst thing is mobile homes.”

This year, 48 deaths have resulted from tornadoes and 35 were in mobile homes.