THE BUREAU of Meteorology is forecasting a drier than average autumn across the majority of the nation, in spite of no clear climate drivers emerging correlated with drier than average conditions.
The mapping for the autumn outlook looks alarming, with vast swathes of the nation less than a 30 per cent chance of exceeding median rainfall for March to May, however tempering this concerning forecast is the fact that the Bureau's skill in forecasting factors such as the El Nino Southern Oscillation is at its lowest in autumn.
There is a slightly higher chance of reaching median rainfall in the coastal strip to the east and south of the Great Dividing Range.
The reason for the dry forecast lies within recent seasons with similar neutral conditions.
Bureau of Meteorology technical lead extended prediction Andrew Watkins said of late neutral conditions had been correlated with drier conditions, particularly in southern Australia.
"Australia's key climate drivers are easing and expected to be neutral over the coming months," he said.
"When our climate drivers are more neutral, autumn rainfall in southern Australia has generally been lower than average over recent decades."
Already, Dr Watkins said drier than average conditions had emerged in late summer through areas such as parts of southern Queensland, western Tasmania and south-west Western Australia.
Looking forward, world forecasting officials are increasingly moving towards an El Nino forming.
The World Meteorological Organization now has a 55 per cent likelihood of an El Nino developing in the June to August period, although the group also cautioned that forecasting skill was low at this time of year.
More immediately, the WMO is tipping a period of ENSO-neutral conditions, with 90pc probability of neutral conditions in March to May, dropping to 80pc from April to June and 60pc May to June.
In the oceans, Dr Watkins said in the Pacific the strong La Nina event of last year was gradually drawing to a close, with neutral conditions likely to return for autumn.
On the other side of the continent the Indian Ocean Dipole is neutral and also has little influence on Australia's climate during the northern wet season, which extends through until April.
Looking back at summer, Dr Watkins said as a rough rule far northern areas were wetter than average and southern areas drier than average.
North Queensland had well above average rainfall this summer. However, rainfall in parts of south-eastern Queensland and north-eastern New South Wales was well below average.
It has been a much drier summer than usual for southern and inland parts of Western Australia, western Victoria and western Tasmania.
There was also the influence of cyclones, with ex-tropical cyclone Ellie brought heavy rainfall and flooding to northern areas of Western Australia, the Northern Territory and Queensland contributing to above average summer rainfall in these areas.
The summer was generally milder temperature wise, highlighted by the fact Sydney's top temperature for the entire summer was just 30.6 degrees, compared to an all-time record of 45, while Perth did not record a single day above 40, where it normally records three to four each summer.