Tornadoes are a global phenomenon. Although the United States experiences the greatest number of tornadoes annually, tornadoes occur regularly in at least 20 countries around the world. Tornadoes form almost exclusively in the mid-latitudes—between 20° and 60° north and south of the equator—where warm air from the tropics mingles with cooler air from the poles, and have been recorded on every continent on Earth except for Antarctica (which lacks the aforementioned warm air).
The true frequency of tornadoes is actually unknown in many countries. While the United States utilizes a robust tornado identification and tracking system, most other countries track tornadoes with much less urgency (or not at all). As such, the list below, which includes countries where tornadoes are known to occur, should be considered inclusive, but not comprehensive.
Countries That Have Tornadoes*:
|Australia||Germany||Paraguay||United Arab Emirates|
*Note that the above list does not indicate frequency. A country that averages nearly 1,200 tornadoes per year (U.S.) may be listed next to a country that experiences only a handful of tornadoes per decade (UAE).
Measuring tornado intensity: The Fujita scale and the Enhanced Fujita scale
Determining the relative power and intensity of a tornado is a challenging process, as most tornadoes exist for only a few minutes to an hour and may not encounter a professional weather station during that time. Instead, tornadoes are often evaluated after the fact based upon data such as Doppler radar measurements and especially on the degree of damage they inflict upon their surroundings (which can be used to indirectly measure the intensity of the tornado's winds).
Tornadoes in the United States, Canada, and a growing number of additional countries are classified using the Enhanced Fujita scale, which assigns tornadoes a rank from EF0 (lowest) to EF5 (highest) by the speed and destructive potential of their winds.
The Enhanced Fujita scale was first introduced in 2007 and is the upgraded successor to the original Fujita scale, which was introduced in 1971 and is still used by many countries. The original Fujita scale uses the same ranking system (F0 to F5) but reduces ambiguity by incorporating more detailed and inclusive guidelines for evaluating tornado damage. Both scales were created by Japanese-American meteorologist Tetsuya Theodore "Ted" Fujita.
Tornadoes in the United States
The United States has the highest number of tornadoes of any country in the world, averaging 1,150-1,200 tornadoes every year. Not only is this total several times higher than that of the #2 country (Canada, at roughly 100 tornadoes per year) it also dwarfs the collective annual average for the rest of the world combined (200-300). The U.S. tornado tally does come with a caveat, in that many other countries lack advanced tornado reporting systems so a number of their tornadoes go unrecorded. However, even if every country adopted a rigorous reporting system, the U.S. would likely remain the global leader by a significant margin.
The United States also experiences tornadoes of greater intensity than any other country. 60-75% of all tornadoes rank as an EF0 or EF1, which are "weak" and cause only 5% of tornado-related deaths in the U.S. Another 35% or so are "strong" EF2 and EF3 tornadoes, which cause roughly 30% of deaths. Finally, roughly 2% of tornadoes in the U.S. reach the "violent" tier and are classified as EF4 or EF5 tornadoes. Though quite rare, violent tornadoes cause approximately 65% of all tornado-related deaths. The United States is the only country in the world to regularly experience tornadoes that classify as an EF4 or EF5.
The Enhanced Fujita Scale for Tornadoes:
|Class||Rank||Wind speeds (3-sec gust)||Approximate frequency||% of deaths caused|
*NOAA frequencies total to 97% rather than 100%. Roughly 3% of tornadoes either leave no damage or leave damage that can't be distinguished from the damage from another tornado. As such, the rank of these "EF-unknown" tornadoes cannot be determined.
While tornadoes can technically appear at any time of year, they occur most frequently in early summer and late spring. Similarly, while tornadoes have appeared in every state of the union at one time or another, they are most common in the Southeast and Midwest of the United States—particularly in Tornado Alley, which includes large portions of Texas, Oklahoma, Kansas, and Nebraska.
The deadliest tornado in recorded United States history occurred on March 18, 1925, when the Tri-State Tornado of 1925 tore a 219-mile swath (the longest yet recorded) through southern Missouri, Illinois, and Indiana, killing more than 695 people and leaving thousands more injured and/or homeless.
Although modern storm tracking and early warning systems greatly reduce the likelihood of such catastrophes, they cannot completely eliminate the risk. For example, the 2011 super outbreak occurred when a single massive storm system produced more than 360 tornadoes (including 4 EF5s and 11 EF4s) from April 25-28, leading to 324 tornado-related deaths across six southern states. In all, the outbreak caused more than $10 billion USD in damage and stretched across more than a dozen states, from Texas to New York.
Tornadoes in Canada
Canada experiences the second-highest number of tornadoes in the world, averaging 80 to 100 tornadoes per year, mostly from March to October. The deadliest tornado ever recorded in Canada appeared ion June 30, 1912 in the city of Regina, Saskatchewan. Rated retroactively at F4 on the original Fujita Scale, the tornado tore through the city's downtown area and damaged structures including the city’s central library, multiple churches, and YMCA, resulting in 28 deaths and more than 300 injuries. Canada is also one of only a handful of countries outside the U.S. to have experienced a documented F5 tornado, which struck Elie, Manitoba in June 2007.
Tornadoes in the England
While the U.S. may have more tornadoes overall, England actually holds the Guinness World Record for the highest number of tornadoes per a square kilometer/mile thanks to its much smaller total land area. According to research conducted by Kelsey Mulder and David Schultz of the University of Manchester, England averaged one tornado for every 4,545 square kilometers (1,754 square miles) per year from 1980 to 2012. During that same time, the entire USA averaged one tornado per 7,693 square kilometers (2,970 square miles) per year.
Area aside, England averages 34 tornadoes in a year, most of which occur in either the Thames Valley near the cities of London and Reading or along the route from Manchester to Boston, close to the Welsh border.
Tornadoes in England tend to measure F0 or F1 on the original Fujita scale (EF0/EF1 on the Enhanced Fujita), slightly weaker on average than tornadoes in the United States and Canada. But "weaker" in tornado terminology is a relative measure and England's tornadoes can still cause significant damage. A notable case is an F2 tornado in Birmingham in 2005, which had wind speeds of up to 157 miles per hour and injured 19 people.
Tornadoes in New Zealand
Tornadoes are infrequent in New Zealand, which averages roughly ten strong tornadoes per year. New Zealand records most of its tornadoes on the North Island. Unlike twisters in the United States, which can track for up to 60 miles and reach speeds of 112 miles an hour, tornadoes in New Zealand cover shorter distances, which results in fewer fatalities overall. The most destructive tornado recorded in New Zealand's history is the 1948 tornado in Hamilton, which damaged 170 houses and killed three people.
Tornadoes in Bangladesh
Bangladesh's climate and topography make it the ideal place for tornadic activities. In addition, Bangladesh is one of the world's least-developed countries, marked by both tremendous population density and typically poor home construction. These factors combine to make tornadoes in Bangladesh particularly dangerous.
The deadliest tornado in recorded history was the Daulatpur–Saturia tornado, which touched down in Bangladesh's Manikganj District on April 26, 1989. Rated at an F3.5-4.0, the tornado traveled roughly 80 km (50 mi) and left 1,300 people dead, 12,000 injured, and more than 80,000 homeless.
Nor was this the country's only deadly tornado. Bangladesh, along with the United States and India, dominates the list of the world's deadliest known tornadoes. Tornadoes in Bangladesh have killed more than 500 people on four separate occasions between 1964 and 1977, and a May 13, 1996, tornado was responsible for 600 deaths and the destruction of thousands of structures.
Tornadoes in Argentina
The South American country of Argentina experiences about seven tornadoes every year. The country recorded its worst tornado in 1973 in San Justo, where more than 54 people were killed and more than 500 homes were damaged. A tornado had struck the same area two decades earlier, overturning a train and injuring 48 passengers.