The positive Indian Ocean Dipole (IOD), which has reinforced the impact of El Nino in Australia since August, has broken down.

The two weather phenomena combined to create an exceptionally warm and dry spring in many areas, leading to increased bushfire risk.

But, as is common at the start of the monsoon season, the positive IOD has decayed rapidly.

Broader Indian Ocean temperatures remain warmer than average, which tends to lead to wetter conditions and could potentially offset the impact of El Nino through the summer.

The Bureau of Meteorology says the El Nino, which is comparable to record events of 1982/83 and 1997/98, is nearing its peak.

Meanwhile, the World Meteorological Organisation says El Nino and climate change have combined to put this year on track to become the warmest on record.

The period between 2011 and this year is the warmest five-year stretch on record, featuring many climate change-influenced heatwaves.

“[This year] is likely to be the hottest year on record, with ocean surface temperatures at the highest level since measurements began,” Secretary-General Michel Jarraud said.

“This is all bad news for the planet. Greenhouse gas emissions, which are causing climate change, can be controlled. We have the knowledge and the tools to act.

“Added to that, we are witnessing a powerful El Nino event, which is still gaining in strength.”

The overall warming impact of El Nino is expected to continue into next year, Mr Jarraud says.