This page lists tornadoes and tornado outbreaks which have touched down in Canada prior to the 21st century. On average, there are around 80 confirmed and unconfirmed tornadoes that touch down in Canada each year, with most occurring in the southern Canadian Prairies, Southern Ontario and southern Quebec. Canada ranks as the country with the second most tornadoes per year, after the US. The most common types are F0 to F2 in damage intensity level and usually result in minor structural damage to barns, wood fences, roof shingles, chimneys, uprooted or snapped tree limbs and downed power lines. Fewer than 5% of tornadoes in Canada are rated F3 or higher in intensity, where wind speeds are in excess of . Prior to April 1, 2013, Canada used a slightly modified Fujita scale, and as of that date the Enhanced Fujita scale, again slightly modified, was put into use to rate tornado intensity, based on the damage to buildings and vegetation.
Each year on average, about 43 tornadoes occur across the Canadian Prairies and about 17 occur across Ontario and Quebec. New Brunswick and the British Columbia Interior are also recognized tornado zones. All other provinces and territories have significantly less threat from tornadoes. The peak season in Canada is through the summer months, (June to August), when clashing air masses move north, as opposed to the spring season in the United States southern-central plains, although tornadoes in Canada have occurred in spring, fall and very rarely winter.
The reported increase in numbers of tornadoes in recent years may reflect more reporting by citizens and media involvement rather than an actual increase in tornado occurrence (although some natural increase has not been ruled out), in addition to better detection technology i.e. Doppler weather radar and satellite imagery. The upswing could also be attributed to other factors, such as improved aerial and ground damage assessment after the fact in sparsely populated areas (particularly the case in remote parts of the Canadian Prairies and Northern Ontario, for example), better trained spotter capabilities and increased use of digital recording devices by citizens. Tornadoes in Canada are enough of a threat for a public warning system to be in place, overseen by the national weather agency, Environment Canada (EC).
For a variety of reasons, such as Canada's lower population density and generally stronger housing construction due to the colder climate, Canadian tornadoes have historically caused fewer fatalities than tornadoes in the United States. The deadliest tornado in Canadian history, the Regina Cyclone of June 30, 1912, killed 28 and injured 300. Urban centres are not immune from the threat of severe tornadoes. Twelve medium to large size Canadian cities have been hit by significant strength tornadoes (F3 or higher), which caused large-scale damage and fatalities: Toronto (1868); Regina (1912); Windsor (1946 and 1974); Sarnia (1953); LaSalle (1956); Sudbury (1970); Woodstock (1979); Lloydminster (1983); Barrie (1985); Edmonton (1987); Aylmer (1994); and Ottawa-Gatineau (1888 and 2018).
All figures for damages are in Canadian dollars.
Before 1850
1792
June 30 or July 1 - the first recorded tornado in Canadian history, an F2, affected the Niagara Peninsula between Fonthill and Port Robinson, Ontario. It levelled houses and uprooted many trees. The tornado cut a path of trees in a west to east line from both communities that became known as "Hurricane Road", which still exists today. 1795 or 1798
??? - an unrated probable tornado touched down near Port Credit, Ontario.
1823
August 21 - an unrated tornado touched down near Cornwall, Ontario, and moved southeast into New York before striking Constable, New York.
1826
August 1 - an unrated tornado crossed Lake St. Clair, moving through Chatham, Ontario, where extensive damage was done.
1828
June 27 - an unrated tornado struck Eastern Ontario in the area of Drummond Centre, Ontario. The tornado destroyed barns and houses, carrying some far distances. An unroofed brick house was carried off its foundation. A strong stone house was partly destroyed. Trees on the third and fourth concession of Drummond Township were uprooted and damaged.
1829
Late May - an F0 tornado struck and destroyed the early settlement of Guelph, Ontario. Development on the settlement was slow to begin afterwards with some recalling little progress in the next three years following the tornado.