A winter weather system dropped 6 inches of fresh snow in some parts of the greater Chicago area Sunday morning, and prompted a ground stop at O'Hare International Airport.

At least the double average snowfall for the period from September 30 to November 30 has fallen in 27 states, data revealed.

The Chicago area is expected to be blanketed in several inches of snow overnight and Sunday morning, likely leaving roads in hazardous conditions.

“Lower Michigan saw widespread snow from Saturday morning through Sunday morning,” the NWS in Grand Rapids said. “The heaviest snow fell Saturday evening and Saturday night. Here is an estimated snow map, and some of the highest reports we have received:”

"A winter storm will approach the Mid Atlantic and Northeast beginning Monday evening," the Weather Prediction Center said.

The National Weather Service collected snowfall data from Saturday, Dec. 6, to Sunday, Dec. 7. A winter weather advisory was issued for parts of southeast Wisconsin.

The Buffalo Bills and Cincinnati Bengals are expected to play in a snow game when they meet on Sunday in Orchard Park.

Snow moved into Iowa Saturday afternoon and continues this evening. Here's a look at snowfall reports so far (not all from the same time): Des Moines Airport: 0.7 (as of 6 p.m.) Remember that not all reports are received at the same time, so more snow likely accumulated since some of these measurements.

Winter weather is here in Iowa, and cold, snowy mornings are officially a regular part of the season. Use this tool to see how much near you.

Bryan Allegretto, a forecaster for OpenSnow, said in an email to SFGATE that November was 4 degrees warmer for Tahoe City than normal, "which is quite warm and contributed to the lack of snowmaking." Significant amounts of new natural snowfall is unlikely in the near term,