Why are tornadoes more frequent in the United States than anywhere else in the world? The main reason is the United States’ unique topography. Dry, cooler continental-based air from the mountains and Canada collide with moist, warm air from the Gulf of Mexico. This creates the perfect environment for tornadoes to form. The differing winds within these air masses cause vertical wind shear, a change in winds with height, which is critical for tornado formation. The area where all of these ingredients come together is often referred to as Tornado Alley, stretching across most of the Central United States. However, tornadoes occur in every state, including Hawaii and Alaska.
Is there nowhere else in the world that has a similar environment? While other places around the world have some favored topographic features for tornadoes, only the U.S. has the perfect combination of land and water features to create bigger and stronger tornadoes than anywhere else. The chart below shows annual tornado frequencies in select countries.
| United States | 1253 |
| Canada | 60-100 |
| United Kingdom | 30 |
| Australia | 20-25 |
| Germany | 10 |
As stated before, the U.S. sees the most tornadoes annually (about 75% of the world’s tornadoes). Canada comes in second place, seeing 5% of the world’s tornadoes. Along with being at a higher latitude and having climatologically cooler temperatures than the central U.S., the Plains and Prairies of central Canada lack the moisture source that is provided to the U.S. by the Gulf of Mexico. This lack of moisture is a factor that limits tornadoes in Canada. The rest of the world produces the remaining 20% of the world’s tornadoes. A few small countries produce a significant number of tornadoes each year, considering their size. The U.K. generally sees weak tornadoes, but has the highest frequency of reported tornadoes per area. The reason that the U.K. usually sees weak tornadoes is because it’s completely surrounded by water. This moderates the climate, so the U.K. doesn’t have a dry air source to create clashing air masses to produce strong tornadoes like the ones that occur in the U.S.
There are other locations across the world where a few tornadoes occur. Mainland Europe’s tornadoes generally stretch from France to Poland, with Germany known for having strong, but few, tornadoes. Bangladesh has been home to several strong and deadly tornadoes with the Himalayan Mountains and Tibetan Plateau providing dry air, and the Bay of Bengal being a moisture source. South America’s Argentina has recorded some of the strongest tornadoes in the Southern Hemisphere. Although Australia is not in the middle latitudes where tornadoes often occur, numerous tornadoes are recorded, most often in tropical cyclones. Tornadoes occur globally, except for Antarctica, but weather enthusiasts will have to visit the U.S. to see the world’s biggest and strongest tornadoes.