Get ready, Chicago—the biggest snowstorm of the season is heading your way.

The dump will start late Thursday and continue through the next day, bringing 8 to 10 inches (20 to 25 centimeters). It’s almost certain to mess with the Friday morning commute and will probably play havoc with air travelers as one of the busiest airline hubs is forced to shovel out.

The storm comes midway through a relatively uneventful winter, at least for parts of the U.S. The western half of the country has logged warmer-than-normal average temperatures, and for most of the East, it’s been pretty typical, according to the National Centers for Environmental Information. While a December cold snap reached deep into the U.S. South and even brought a dusting of snow to Houston, there haven’t been many blockbuster blizzards in the Midwest or the big East Coast cities. Until now.

A broad arctic front is “draped” across the Midwest, said Bob Oravec, senior branch forecaster at the U.S. Weather Prediction Center in College Park, Maryland. “They haven’t had a big snow this year,” he said. “It will be the biggest snow of the season.” Detroit also may get as much as 10 inches.

Heavy Chicago snow can spread misery to shippers and travelers well beyond the city, which is a major interchange for rail traffic. Air traffic delays and cancellations are mounting at its two airports and that will probably ripple throughout the system, disrupting flights across the U.S.

At least 440 flights have been canceled around the U.S. Friday with 382 of them scheduled to arrive and depart from Chicago’s two airports, according to FlightAware, an airline tracking service.

Southwest Airlines Co. has scrubbed 350 flights through mid-day Friday at Chicago’s Midway International Airport in advance of the snow, said Alyssa Eliasen, a spokeswoman. Midway is Southwest’s busiest airport, with up to 259 daily departures.

Friday Commute

Locally, the storm’s worst will probably fall on people trying to get to work Friday.

“Travel will be very difficult to impossible at times, including during the morning commute,” the National Weather Service said in a winter storm warning. It’s not expected to impact New York or the other East Coast cities.

The storm is growing along an arctic front that will send temperatures plunging in Chicago and across the Midwest. The low in the city is expected to sink to 7 degrees Fahrenheit (minus-14 Celsius) by late Sunday, the weather service said. Colder readings will grip the upper Great Plains into the western Great Lakes from Feb. 13 to 22, according to Radiant Solutions in Gaithersburg, Maryland. Meanwhile, warmer-than-normal temperatures will likely cover much of the southern U.S., even stretching up the East Coast as far as Boston, during the same time period.

The looming storm isn’t really that powerful, Oravec said.

“Sometimes you don’t need a big low to get heavy snow,” he said.