Fall weather has arrived in Chicago and residents are bracing for what could be a colder, wetter winter due to the arrival of La Niña.

La Niña refers to the colder ocean water off the coast of Peru, which causes various weather activities in regions around the world via the jet stream. Typically, La Niña brings colder temperatures and more precipitation to winters in the northern U.S., while southern states see warmer and drier forecasts.

According to forecasts from the National Weather Service, La Niña has about a 60% chance of emerging in late November and could last until March.

This year, La Niña is expected to be weaker than normal, making weather forecasts difficult to predict this far in advance, said National Weather Service meteorologist Zachary Yack.

“If it’s a little bit weaker, there’s a chance it’s atypical from that perspective. It depends on how each storm approaches,” Yack said.

While La Niña in the Chicago area often signals colder weather in the winter, this year’s weaker pattern could lead to different impacts on temperatures.

“We’ll probably get some cold snaps, but it could also be above-normal temperatures,” Yack said.

The Old Farmer’s Almanac, a reference guide for farmers and gardeners, predicts that winter this year could be mild in terms of temperature and precipitation in the US – but due to La Niña combined with El Niño’s Southern Oscillation, Chicago’s story may be look different. editor-in-chief Sarah Perrault said.

“The polar vortex is moving, Chicago is actually very different from the rest of the country,” Perrault said. “The rest of the country will be warmer, while Chicago will be colder.”

The coldest periods for the Chicago area are expected to be in early and late November, early December and from late January to early February, the Almanac predicts.

According to the weather service’s latest forecasts, much of the Midwest — including Chicago — has an equal chance of above-average and below-average temperatures from December through February. The same forecasts indicate above average precipitation chances in the Chicago area, but the Almanac’s forecast expects less snowfall and overall precipitation throughout the winter.

The weaker La Niña could mean fewer storms throughout the winter, Yack said, but that’s impossible to say for sure.

Yack said his advice to residents remains largely the same during any Chicago winter: Follow the weather forecast and prepare for winter storms when they are expected.

Perrault said Chicagoans need to stay prepared throughout the season.

“Everyone should always stay united, no matter what,” she said. “We say, ‘Don’t wait for a snowstorm to buy your sled.'”