Winter is over. Wet sums it up over the east of the country, though it was still warmer than the long-term average. Up north, it was a cool one.

Darwin and Kununurra both recorded their coldest 'winter' in over 8 years. Four seasons and a June-to-August winter are concepts based on a temperate climate and don't make a lot of sense in the tropics. Indigenous locals recognise 6 seasons, with the coldest or 'winter' season being July and August, termed Wurrkeng over the Top End. Based on this definition of 'winter,' Darwin averaged a minimum of 18.9°C and maximum of 31.3°C and Kununurra a minimum of 12.3°C and a maximum 31.6°C over the season.

The coldest month by far was July, clocking in at the coldest since 1965 for Darwin and since 1985 for Kununurra. The three-week stretch of days below 30°C between late June and mid-July was unprecedented for both towns. Kununurra's 6.0°C minimum on both the 8th and 12th July was the coldest on record (records back to 1972). Darwin's 14.1°C on the morning of 24th July was the coldest since 2019.

The cause was easterly winds. Easterlies dominated winter both up north and down south and their predominant (and unseasonal) presence was a large driver of the wet winter over Queensland and NSW. Easterlies dry out as they cross the interior then, when they reach the tropics, replace more humid air. This drier air then allows the atmosphere to cool more than it otherwise would. Frequent southeasterly wind surges this past winter prevented intrusions of more humid northerlies that often intermittently affect the tropics, even during the winter dry season.

After the tropical cold spell ended late July, it has steadily become warmer and more humid.

With a La Niña looming and a negative IOD declared, an early monsoon onset could be imminent. Regardless, 'winter' up north is giving way to the much warmer and more humid pre-Build-Up or Kurrung.

Image: Mean temperature anomalies over the standard winter (1 June to 31 August) for 2022 showing cold pools over the central tropics. From bom.gov.au