Severe Weather 101

Step into the wild world of weather!

What is a wall cloud? What's the difference between a watch and a warning? Is it ever “too cold to snow”? Learn all about thunderstorms, tornadoes, hail, lightning, floods, damaging winds and severe winter weather.

panoramic image of a mesocyclone thunderstorm


There can be as many as 40,000 thunderstorms each day around the world. They are most common in the U.S., where they can produce tornadoes, floods, lightning and damaging winds.

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tornado in a rural area at sunset


Much about tornadoes remains a mystery. They are rare, unpredictable and deadly. The U.S. has more tornadoes than anywhere else in the world.

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two men in a boat in flood waters; there is a single-story wood-frame house behind them; the floodwater level is about halfway up the walls of the house


Except for heat-related fatalities, more deaths occur from flooding than any other weather-related hazard.

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many lightning strikes over a city at night


Lightning is one of the oldest observed natural phenomena on earth. At the same time, it also is one of the least understood.

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hail stones in grass with a U.S. quarter next to them; the hailstones are all larger than the coin


Hail can cause billions of dollars of damage to structures, crops and livestock.

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small private plane turned upside down in front of a demolished building

Damaging Winds

Straight-line winds are responsible for most thunderstorm damage. These winds can cause as much damage as a tornado.

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vehicles on a mountain road in heavy snow

Winter Weather

Forecasting winter weather accurately is very difficult because a degree or two of temperature change can mean the difference between snow or freezing rain.

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