Key Criteria for a Blizzard:

Wind: Sustained wind or frequent gusts of 35 miles per hour (30 knots) or greater.
Visibility: Snow (falling or blowing) reduces visibility to less than 1/4 mile (400 meters).
Duration: These conditions must persist for a minimum of 3 consecutive hours.

Important Distinctions:

No Heavy Snow Required: A blizzard does not require heavy, falling snow; it can be caused by strong winds picking up already fallen snow, known as a ground blizzard.
Temperature: While often associated with extreme cold, there is no specific temperature requirement to qualify as a blizzard.
Severe vs. Official: A blizzard warning is only issued when these specific, dangerous conditions are met, distinguishing them from a regular heavy snowstorm.