You may have heard "blizzard" in the forecast recently. But what does a "blizzard" actually mean? Believe it or not, the National Weather Service has a pretty strict definition of a blizzard. For a blizzard to occur: - There must be considerable snowfall, although there is no specific threshold that must be met. - Wind speeds have to reach above 35 miles-per-hour - Visibility needs to drop to one-quarter mile or less - These conditions must last for at least three hours | Indiana Michigan Power