The fall has been dramatic across the United States, with wildfires on the West Coast and hurricanes in the South. Last week, the Northeast experienced a wave of springlike weather. So what's in store for winter, which offically kicks off on December 21? National Weather Service forecasters have seen cooler-than-normal water temperatures in the Pacific, which has prompted a La Nina watch. A La Nina weather pattern can bring in unusual temperatures. According to their predictions, much of the U.S. will have a balmy winter, but it could get colder than normal in some areas like the Pacific Northwest.