Forecasters are predicting another winter wallop to the Chicago area, with up to 8 inches of new snowfall — and maybe some thunder — on Monday.

A winter storm warning across all of northern Illinois and Northwest Indiana will be in effect from 9 a.m. until 9 p.m. in a slippery start to the week, according to the National Weather Service.

Between 4 and 8 inches are expected to pile up, with totals closer to 10 inches in some isolated areas, according to the weather service.

Forecasters are warning of “extremely difficult travel conditions” Monday afternoon as 2-3 inches of snow could fall per hour at times, and even thunder will be possible during times of the heaviest snowfall.

By 10:30 a.m., 880 flights were canceled at both airports. About 680 flights are canceled at O’Hare, where flights are running about 45 minutes late, according to the city’s Department of Aviation. About 200 flights are canceled at Midway where passengers are delayed up to two hours.

After Monday’s snow comes a warmup, with Tuesday high predicted to hit 40, followed by 38 on Wednesday, a relative heat wave in the middle of one of Chicago’s coldest winters on record.

The warmth could bring new problems, though, with a rapid snow melt possibly leading to flooding.

The current snow pack on the ground in most of northern Illinois is equal to between 1 and 4 inches of water if it melts completely, according to the weather service.