The most destructive fires are usually preceded by extreme high temperatures, low relative humidity and strong winds, which combine to create ideal conditions for the rapid spread of fire. Severe fire storms are often named according to the day on which they peaked, including the five most deadly blazes: Black Saturday 2009 in Victoria (173 people killed, 2000 homes lost); Ash Wednesday 1983 in Victoria and South Australia (75 dead, nearly 1900 homes); Black Friday 1939 in Victoria (71 dead, 650 houses destroyed), Black Tuesday 1967 in Tasmania (62 people and almost 1300 homes); and the Gippsland fires and Black Sunday of 1926 in Victoria (60 people killed over a two-month period). Other major conflagrations include the 1851 Black Thursday bushfires, the 2006 December bushfires, the 1974–75 fires that burnt 15% of Australia, and the 2019–20 bushfires. It is estimated that the 2019–2020 bushfires led to the deaths of at least 33 people and over 3 billion animals.