Here's a list of the most costly - for insurers - disasters in Canada. Smoke drifted as far south as North Dakota. Fifteen years prior, a fire broke out in the St. Lawrence Market area of the city, but it was much smaller in size. No one, unless, of course, the freighter was carrying 2,300 tons of ammonium nitrate fertilizer (this is the same stuff that was used in the Oklahoma City bombing in 1994)—the result being the largest industrial explosion in U.S. history. The Halifax Explosion was a disaster that occurred in Halifax, Nova Scotia, Canada, on the morning of 6 December 1917. On average, about 6,000 forest fires occur in Canada every year. While wildfire is a natural and important part of the forest ecosystem, when it encroaches on human dwellings it can have disastrous effects.Over the course of Canadian history, several major forest fires have destroyed large amounts of timber and property, and taken many lives. The single largest recorded fire in North American history was the Chinchaga fire of 1950, which burned up to 1,700,000 hectares in both northern British Columbia and Alberta. According to Stephen Pyne in Awful Splendour, his history of fire in Canada, “The boreal region is home to Canada’s largest fires, its greatest fire problems, and its most distinctive fire regimes, the ones that define Canada as a fire nation…. The Canadian National Fire Database (CNFDB) is a collection of forest fire data from various sources; these data include fire locations (point data) and fire perimeters (polygon data) as provided by Canadian fire management agencies (provinces, territories, and Parks Canada). Who would think that a small fire in the hold of a docked freighter would cause such a problem? The Fort McMurray wildfire was the most expensive disaster in the country's history for insurance providers. Of Canada’s approximately 6,000 annual fires, just over half are started by people (most by accident), and just under half by lightning.Being generally less accessible, the average fire started by lightning is several times as large as a human-caused fire. To learn more about the Great Fire of Toronto of 1904, listen to today's episode of "This Day In Weather History." Basic Facts. The fire, dubbed the Great Fire of Toronto of 1904, is the city's largest fire to date. The massive explosion killed more than 1,800 people, injured another 9,000–including blinding 200–and destroyed almost the entire north end of the city of … Forest Fires . Northwest Territories, 2014: By area, still the most hectares burned in a single fire season in Canada at 3.5 million hectares. It cost $55 million to fight. A century later, the so-called Great Matheson Fire of 1916 remains the deadliest in Canadian history.