( CNN ) -- Bundle up ; it 's about to get chilly . We 're not talking about a nip in the air , either . By midweek , locales throughout the United States will have seen high temperatures up to 20 degrees below average , according to CNN and National Weather Service forecasters . As a cold front moves through the Plains and Great Lakes toward the Eastern United States -- bringing some light snow , especially in the higher elevations of the Appalachian Mountains and in areas impacted by lake effect -- temperatures are expected to drop significantly beginning Monday . The Plains could see high temperatures 15 to 20 degrees below average Monday and Tuesday . By Wednesday , the chill will grip the Northeast and Southeast , pushing the mercury about 20 degrees below average . `` A strong front extending from the Great Lakes to the Central Plains will move eastward off the East Coast and southward to the Gulf of Mexico by Tuesday evening . Cold high pressure over South-Central Canada will sink southward to the Middle Mississippi Valley/Central Plains also by Tuesday evening , '' according to the National Weather Service . Residents from the Missouri Valley to the northern Rocky Mountains can expect snow Monday , the weather service said . Rain or snow can be expected Tuesday through much of the Great Lakes area , down to Tennessee and eastward toward the Carolinas and southern New England . `` Meanwhile , a front over the Eastern Pacific will move to the West Coast and dissipate on Tuesday morning . The system will produce light to moderate rain along the West Coast from the Pacific Northwest to Northern California late Monday night to Tuesday morning , '' the weather service said . The Centers for Disease Control and Prevention has tips for how to stay warm and what to do in the event of cold-related illnesses .
Some high ##s in U.S. may dip to 10 degrees below the average . Rockies , Midwest and areas impacted by lake effect could see some snow . Plains , Northeast and Southeast may see most anomalous temperatures .