The latest analysis from NASA and the National Oceanic and Atmospheric Administration comes from altimeter readings of sea surface heights in the Pacific Ocean.
Water expands when it heats up and contracts when it cools down, causing changes in sea surface heights.
â€” ABC News (@abcnews) October 16, 2015
The two strongest El Ninos that we know of occurred in 1982-83 and 1997-98.
Both events had significant global impacts including droughts, floods and cyclones.
The 2015 data shows surface waters cooling off in the Western Pacific and warming significantly in the tropical Eastern Pacific.
Average sea surface temperatures were 1.5 degrees Celsius above normal from July to September, ranking third behind 1982’s 1.6 degrees Celsius and 1997’s 1.7 degrees Celsius readings.
The El Nino is being further strengthened by weakening easterly trade winds allowing stronger westerlies to push warmer air from the western and central Pacific towards the east.
The Australian Bureau of Meteorology said the El Nino should peak in late December before declining in the first quarter of 2016.
El Nino usually brings below-average spring rainfall across eastern Australia, and increased spring and summer temperatures across southern Australia.
The Bureau of Meteorology is predicting that the drying pattern in south-eastern Australia will be exacerbated by the warming of the western Indian Ocean.
This pattern, known as a positive Indian Ocean Dipole, is now at levels not seen since 2006.