The tiny droplets of water freeze onto crystals, building them up. Then, they fall to the Earth as snow. When it is 39 degrees Fahrenheit on the Earth's surface, the snow will land before it melts. In order for snow to build up on the ground, it has to be much colder. According to the U.S. National Weather Service, winds of 35 mph or more and visibility of .25 miles or less are conditions that, if they endure for three hours, define a blizzard.
Blizzards can cause serious damage.
The weight of snow can make buildings collapse. Crops freeze, and livestock can be killed. Sometimes, businesses have to be closed. The roads are blocked and airports shutdown, so all traveling can be stopped. Sometimes, people can't even get to the hospital.