Blizzard is a blinding snowstorm with strong, cold winds. A blizzard occurs when a cold air mass moves out of the Arctic into the Temperate Zone. The advancing heavy, cold air forces the warmer, moist air to rise along the boundary between the two air masses. This boundary is called a cold front. The rising action produces a heavy snowstorm, which is accompanied by cold north winds. Many blizzards follow a period of unusually warm weather in winter.