NASA figures released over the weekend show the global temperature of land and sea was 1.11C warmer in April than the average temperature for the same month during the period 1951 to 1980.
This new record broke a previous one by 0.24 degrees celcius, which was set in 2010.
The warm autumn has continued in May, with temperatures in Australia's major cities on some days as much as six degrees above usual.
Australian Bureau of Meteorology climatologist, Blair Trewin, said the El Nino weather system was the catalyst for the warm conditions.
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The weather system is characterised by the release of warm water across the Pacific Ocean, and it's believed that rapid global warming also added to these temperatures.
"We always expected that the next time we got a very strong El Nino with the warming trend, that we would be seeing global record temperatures and that's indeed what has happened," he said.
"Here in Australia, last month's mean temperature was the second warmest on record - two degrees above average, and it was also the eighth driest April we've experienced, with rainfall almost seventy per cent below average."
Mr Trewin said the warmer temperatures were expected to continue into winter.
“We’ve seen very consistent warmth this month in most of the major south-eastern cities, not so much records for individual days for this time of year," he said.
"At the moment our outlook is a period in July that is leaning quite strongly towards warmer than normal temperatures, particularly overnight, a bit less so for daytime temperatures."
