Illinois residents should prepare for a chilly holiday season with a chance of flurries, thanks in part to La Niña .

Experts forecast a wetter-than-normal winter season throughout the state, with cooler temperatures as we inch towards December. Here's what we know.

What is La Niña?

La Niña begins at the central Pacific Ocean’s surface. When the ocean's temperatures cool (which usually happens every three to five years) that affects tropical rainfall, which in turn affects weather patterns around the world, according to the NWS.

The wave-like jet stream above North America tends to then shift farther north into parts of western Canada, Casey Crosbie, a meteorologist with NWS Indianapolis , told the Indianapolis Star . This causes the downstream storm track to curve down into

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