The floods were caused by heavy rain from tropical cyclone "Tasha" that joined with a trough during a La Niña event. La Niña is an unusual weather pattern, which brings wet weather to eastern Australia. The 2010 La Niña was the strongest since 1973. This caused heavy rainfall across Queensland. December 2010 was the wettest on record, with 107 places getting their highest rainfalls ever. The state average rainfall level of 404.7mm was much bigger than the old record of 369mm set in 1975. 2010 was also recorded as the state's wettest spring since 1900 and Australia's third wettest year. Flooding started across parts of the state in early December. On 28 December a monsoonal trough crossed the coast from the Coral Sea, bringing very heavy rain from the Gulf of Carpentaria to the Gold Coast.