In the United States, the National Weather Service defines a blizzard as sustained winds or frequent gusts reaching or exceeding 35 mph which lead to blowing snow and cause visibilities of 1/4 mile or less, lasting for at least 3 hours. Temperature is not taken into consideration when issuing a blizzard warning, but the nature of these storms is such that cold air is often present when the other criteria are met. Temperatures are generally below 32 °F.

According to Environment Canada, a winter storm must have winds of 25 mph or more, have snow or blowing snow, visibility less than 500 feet, a wind chill of less than −15 °F, and all of these conditions must last for 3 hours or more before the storm can be properly called a blizzard.

Many European countries, such as the UK, have a lower threshold: the Met Office defines a blizzard as "moderate or heavy snow" combined with a mean wind speed of 30 mph and visibility below 650 feet.

Meteorologists refer to blizzard-like conditions with no snow falling as a ground blizzard, because all the snow is already present at the surface of the earth and is simply being blown by high winds. Ground blizzards require large expanses of open and relatively flat land with a sufficient amount of accumulated and loosely packed, powdery snow to be blown around.

NOAA: The Sioux Falls Forecast Office issues a blizzard warning when the following conditions are expected to occur for 3 hours or more:

   1. Sustained wind speeds of 35 mph or more, or frequent gusts to 35 mph or greater;
   2. Considerable falling and/or blowing snow that reduces visibility frequently to 1/4 mile or less.