"The outlook is indicating strong chances of getting above those averages," Ms Gamble said.

"To put that in perspective, in January for the whole of NSW it was about 5 degrees above average, which is pretty remarkable."

January was the hottest month on record for Australia, while December was the second hottest month ever recorded.

In 2018, NSW had its second warmest autumn on record, with the statewide mean temperature for the period 1.88 degrees warmer than average. The hottest autumn for the state was recorded in 2016.

"Given the current climate, and given the outlook and recent trends, there's a good chance it will likely be in the top 10 [hottest autumns]," Ms Gamble said.

Autumns trending drier

While the climate outlook shows there is no strong tendency for autumn being either wetter or drier than usual in southern Australia, Ms Gamble said longer-term trends showed the country was experiencing drier autumns.

"Since 1990, 24 out of 29 autumns have had below average rainfall in south-eastern Australia, so we are tending to see a drier than average autumn," she said.

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Autumn in 2018 in NSW was the state's eighth-driest autumn on record. March, April and May were all drier than average, with rainfall for the whole season 60 per cent below average.

As well as trending drier, the bureau climatologist said the "autumn break" - usually, the first significant rainfall for the winter - was tending to occur later.

Ms Gamble said cooler temperatures in the oceans off Western Australia tended to create a drying influence.

Looking further into the year, Ms Gamble said there was twice the normal likelihood of El Nino occurring, which would lead to warmer months through winter and beyond.

"We are starting to see some early signals of a potential for El Nino developing later in the year, potentially late autumn or early winter," she said.

"The next few months is quite a pivotal point for what is going to drive our weather for the remainder of the year."