The list ranked according to highest death toll. The deadliest blizzard occurred in Iran in 1972 and 4.000 people lost their lives. A blizzard is a severe winter storm condition characterized by low temperatures, strong winds, and heavy blowing snow. Blizzards are formed when a high pressure system, also known as a ridge, interacts with a low pressure system; this results in the advection of air from the high pressure zone into the low pressure area.