Australia Weather News

The chance of a La Nina weather pattern forming later this year is now at 50 per cent, around double the normal likelihood.

The Bureau of Meteorology's El Nino Southern Oscillation Index (ENSO) wrap-up came out today and the bureau has declared a La Nina watch.

La Nina is a phase of ENSO, typically associated with wetter conditions for Queensland and the eastern states.

But the bureau is not suggesting there will be above average rainfall this summer.

Extended and long-range forecasts manager Andrew Watkins said typically during the late spring and summer, a La Nina would bring more rainfall, particularly to Queensland.

"But this season, at the moment at least, the Indian Ocean is opposing that signal coming out of the Pacific Ocean," he said.

"So at the moment our odds are still around about the 50 per cent mark of getting above normal rain, so not really going for the extreme rain we've seen in past La Nina events."

Dr Watkins said La Nina usually brought warmer temperatures in south-east Australia and cooler temperatures in Queensland, due to more cloud cover.

Typically cyclone numbers might increase as well, but this year cyclone numbers were expected to stay in the 10–13 range that has already been forecast.

How is this season looking compared to previous years?

Dr Watkins said this year was different to the La Nina experienced from 2010 to 2012.

During those years there was a strong La Nina that combined with other complementary systems and led to the wettest two-year period in Australia's recorded history.

"We saw all the ducks lining up in the pond. This year it's just the chance," he said.

"Remember we are only at watch at the moment, of a weaker, possibly short-lived La Nina.

"The other indicators are pretty neutral really."

Fire outlook remains the same

The La Nina watch does not necessarily change the fire outlook for this season either.

"At the moment we are still only a watch, we are not actually in a La Nina event," Dr Watkins said.

"We haven't really seen conditions start to cool down at all.

"With continuing high temperatures, dry soils and drying out vegetation, the fire risk is still quite high. We will need to assess that as we go through the event."

This summer might be wetter than usual or it might end up being drier, but today's wrap-up is not enough to say definitively either way.

The bureau's last climate outlook, issued on October 12 for November to January, said overall Australia did not have increased chances of a wetter season.

The next climate outlook is due out on Thursday.

The bureau said that if a La Nina did occur this year, it was likely to be short and weak.

ABC