Hot, sticky, storm-spawning weather kicked off the unofficial start to summer Monday over the eastern half of the United States. Temperatures in the 90s could register as far north as the lower Great Lakes and southern New England, making Memorial Day the first 90-degree day of the year for New York, Pittsburgh and Toledo, AccuWeather.com said. Besides carrying water bottles and seeking shade, residents across the Northeast down into North Carolina could expect their Memorial Day to be pocked by thunderstorms, forecasters said. Chilly rain could renew the threat of flooding across Montana and western North Dakota -- and even snow in the higher elevations of Utah, AccuWeather.com said. Violent thunderstorms also threatened Memorial Day plans from the eastern Dakotas and western Minnesota into western Kansas, forecasters said. Gusty wind were expected to keep the risk of fire high across New Mexico and western Texas, but not the rest of the southern Plains because of high humidity, AccuWeather.com said. Brutal storms pounded south-central Michigan Sunday, zapping power to more than 100,000 utility customers and leaving a path of destruction through Battle Creek, Mich., CNN reported. About 104,000 customers were without power as of 9:30 p.m. Sunday because of the powerful storms that moved across the state, the Kalamazoo (Mich.) Gazette reported. The fast-moving storm felled hundreds of trees and damaged buildings across Battle Creek, but did not cause any serious injuries, the Battle Creek Enquirer reported. Two Battle Creek police officers were injured when a tree fell as they were making a traffic stop during a shooting investigation, police said. One officer was treated for a cut to the arm and the other for a concussion. Severe weather also pummeled the Chicago area, forcing the cancellation of 450 flights as of Sunday evening, and delaying some flights for more than an hour at Chicago O\'Hare International Airport, the Chicago Tribune reported. Midway International Airport also reported delays of between 30 and 40 minutes. A flood warning issued for the Chicago metro area Sunday expired early Monday, the National Weather Service said.