The Bureau of Meteorology's latest Climate Driver Update says the El Nino and positive Indian Ocean Dipole (IOD) have strengthened since its last update.  

The IOD index measured water temperature at +1.85°C, up from +1.45°C at the last update on September 26, marking the sixth-highest value since 2001.   

The bureau expects temperatures to have reached near peak but says the positive IOD will continue until December, bringing reduced spring rainfall to central and eastern Australia.   

It says ocean indicators firmly exhibit the ongoing El Nino state, which is expected to continue until February, with global sea surface temperature (SST) expected to reach above 2.1°C in January.  

"Overall, there are signs that the atmosphere is responding to the warm SSTs over the Pacific and coupling of ocean and atmosphere is occurring," the bureau said.  

"This coupling is a characteristic of an El Nino event and is what strengthens and sustains an event for an extended period."  

The bureau says the Southern Annular Mode index is currently neutral and projects it to remain neutral ahead of the next climate driver update on October 24.   

A concurrent El Nino and positive IOD brings notably drier conditions across western, northern and southern Australia for the summer, increasing the fire and drought risk.