We’re less than a month away from the southern hemisphere winter. But you’d be forgiven for thinking summer was only last week.

April was unseasonably warm and dry across Australia. Temperatures were above average or very much above average for most of the country.

New South Wales had its second-driest April on record, while Bairnsdale in Victoria’s typically wet Gippsland region only recorded 5.4mm in rainfall in April, the lowest since since 1943.

So why has the weather been so unseasonally warm? And what will winter look like?

The dry April came as a stark contrast to a very wet February and March. In late February, a low pressure system from the tropics stalled over central Australia, causing widespread heavy rainfall. Kati Thanda-Lake Eyre began to fill for the second time in two years and the desert turned green.

But during April, persistent high pressure systems sat over large areas of eastern Australia. Air descends within high pressure systems, stopping clouds forming. When high pressure systems are above us, we tend to experience warm sunny days and no rain.

At night, the lack of clouds means more of the day’s heat absorbed by land and water radiates back out to space.........

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