When Does a Snowstorm Become a Blizzard?

The Difference Between a Snowstorm and Blizzard

Blizzard

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Every year, as the snow begins to fall, people start tossing around the word blizzard. It doesn't matter if the forecast is calling for one inch or one foot; it is referred to as a blizzard.

But what exactly makes a snowstorm a blizzard? And how is it different from your average winter weather? 

As is the case with most weather phenomenon, there are strict parameters that define what truly is a blizzard.

Blizzard Classification Around the World

It's worth noting that the definition of a blizzard varies between countries.

  • The United States of America: The National Weather Service categorizes a blizzard as a severe snow storm with strong winds and blowing snow that limits visibility.
  • Canada: The Environment Canada defines a blizzard as a snowstorm that lasts for at least three hours with winds blowing at or greater than 25 mph, accompanied by temperatures below -25˚C or -15˚F and visibility of fewer than 500 feet.
  • The United Kingdom: A blizzard is a storm that produces medium to heavy snowfall with winds of 30mph and visibility of 650 feet or less.

Characteristics of a Blizzard

Thus, it's the strength of the wind that determines whether a storm is a blizzard or just a snow storm — not how much snow is dumped on a given area.

To put it in technical terms, for a snowstorm to be characterized as a blizzard, it must create winds that gust at speeds greater than or equal to 35 mph with blowing snow that reduces visibility to one-quarter mile or less. A blizzard also often lasts for at least three hours.

Temperature and snow accumulation are not taken into account when determining whether or not a storm is a blizzard.

Meteorologists are quick to point out that it doesn't always have to be snowing for a blizzard to occur. A ground blizzard is a weather condition where snow that has already fallen is blown around by strong winds, thereby reducing visibility. 

It is the winds of a blizzard combined with the snow that causes the most damage during a blizzard. Blizzards can paralyze communities, strand motorists, tear down power lines, and in other ways damage economies and threaten the health of those affected.

Where Blizzards Are Common in the U.S.A

In the U.S. blizzards are most common in the Great Plains, the Great Lakes states, and in the Northeast. Northeastern states even have their own name for severe snowstorms. They're called nor'easter there.

But again, while nor'easters are often associated with large amounts of snow, what truly defines a nor'easter is the wind — this time the direction rather than the speed. Nor'easters are storms that affect the northeastern region of the U.S., traveling in a northeastern direction, with winds coming from the northeast. The Great Blizzard of 1888 is considered one of the worst nor'easters of all time.