El Nino has arrived, and it may combine with other weather systems to create severe bushfire conditions in parts of Australia.

The Bureau of Meteorology says tropical Pacific temperatures have reached El Nino thresholds for the first time since March 2010.

El Nino is most often associated with decreased rainfall in eastern Australia and higher temperatures in the south, increasing the risk of heatwaves, drought and bushfire.

Climate Monitoring Manager Karl Braganza told insuranceNEWS.com.au the bureau is gearing up for a dry summer, although briefings with emergency services will not take place until August.

He says in the southeast, the Indian Ocean Dipole (IOD) can be as influential as El Nino, with a positive IOD resulting in much less rainfall.

“When you get both [El Nino and positive IOD] together, that’s pretty much a guarantee of bushfire conditions,” he said.

The IOD is currently in a neutral phase, but positive events are more likely during El Nino.

Bushfire and Natural Hazards Co-operative Research Centre CEO Richard Thornton told insuranceNEWS.com.au this latest El Nino will affect his organisation’s seasonal bushfire outlooks.

“These climatic effects will be taken into account when our outlooks are released in the coming months.”

Dr Thornton says the effective communication of long-term weather conditions is subject to ongoing research.

“It is a different form of communication to the warning messages that alert communities to an actual real hazard threat on their doorstep,” he said.

This El Nino has started earlier than usual – typical events begin between June and November – and it is expected to strengthen during the winter.

However, a strong El Nino does not necessarily mean the impact on rainfall will be more severe.

And the effects will not be felt immediately, with the bureau’s May-July climate outlook indicating wetter than average conditions for much of the country.

El Nino events feature rising temperatures in the tropical Pacific, both at the surface and below. Pacific surface pressure rises in the west and falls in the east, while trade winds weaken and sometimes reverse.

The conditions can last for as little as six months or as long as two years, and on average they occur every 3-5 years.

There have been 26 El Nino events since 1900, 17 of which have brought widespread drought.