SYDNEY (REUTERS) - Australia's weather bureau said on Tuesday (Nov 23) a La Nina weather phenomenon had developed in the Pacific Ocean for the second year in a row that could bring above average rainfall across the country's centre, north and east.

La Nina is typically associated with greater rainfall, more tropical cyclones, and cooler than average temperatures in the equatorial Pacific Ocean.

The weather event could boost Australia's wheat yields. In September, the country lifted its wheat forecast for this season by 17 per cent to near record levels, citing favourable weather.

A wetter than usual end to the year could also result in a less severe bush fire season.

"Back-to-back La Niña events are not unusual, with around half of all past events returning for a second year," Mr Andrew Watkins, the Bureau of Meteorology's head of operational climate services, said in a statement.

La Nina events normally last about a year but climate models suggest this year's pattern will be short-lived, persisting until the late southern hemisphere summer or early autumn of next year, Mr Watkins said.

"Every La Nina has different impacts, as it is not the only climate driver to affect Australia at any one time," he said.

The United States weather forecaster last month said La Nina conditions had developed and there was an 87 per cent chance of the weather pattern continuing through the December to February period.

Australia's weather bureau had moved its La Nina status to "watch" in September and upgraded it to "alert" last month.

A low-pressure system early this month dumped 50mm to 150mm of rain in some parts of the south-east, the highest in years, triggering floods across parts of Queensland and inland New South Wales states.

"A La Nina should translate into a lower risk of bush fires and extreme heatwaves over the eastern states this summer... however, we can expect an increased likelihood of flooding rains and tropical cyclones," said Professor Matthew England from the University of New South Wales Climate Change Research Centre.