However, while it is weakening, it is unlikely that there will be a return to the drier El Nino pattern this year, according to the Bureau of Meteorology (BOM).

BOM climatologist Grant Beard said it was fairly typical of La Nina events to begin to deteriorate in the autumn.

“The peak effects of La Nina generally start in mid-winter and run through to mid-summer, decreasing through the autumn.”

He said, already, the Pacific Ocean had warmed slightly, and the Southern Oscillation Index (SOI), while still strongly positive, had also come back a bit. Trade winds have also declined. All factors are consistent with a breakdown of La Nina.

Mr Beard said the 2010-11 La Nina event had been one of the strongest on record.

“There’s a cluster of three or four events in the past century – it is difficult to separate them in terms of intensity, as there’s not a lot of accurate data prior to 1950.

“However, this year has a lot of parallels to 1918, which was the last time a Category 5 cyclone landed in Queensland.”

Moving forward, Mr Beard said there were two likely scenarios, either there could be a return to neutral conditions, or a weaker La Nina could redevelop.

“There have been several periods over the past century where there has been a three-year wet period, such as 1973-5, 1954-6 and 1916-8.”

La Nina and El Nino patterns have most relevance to weather on the eastern seaboard.