Wet and stormy weather will spread over parts of every Australian state and territory this week, June 15-21, as a powerful low pressure system and northwest cloudband impact the country.

A slow-moving upper-level trough interacting with a steady feed of tropical moisture will cause a large northwest cloudband to form over Australia this week. This band of cloud and rain will be supported by a surface-based low pressure system centred to the south of Australia, which will also deliver an injection of cold air and blustery winds for some parts of the country.

The map below shows mean sea level pressure combined with precipitable water (a measure of moisture availability in the atmosphere) in the middle of this week, showing the low pressure system to the south of Australia and moisture-laden air extending across the country from the northwest to southeast.

Monday to Wednesday: Rain building in Australia’s west, south and interior

Cloud and rain will build over a broad area of western and southern Australia on Monday and Tuesday as the low pressure system and northwest cloudband develop.

The heaviest rain during Monday and Tuesday is likely to fall over northern Tasmania, southern and western districts of SA, and along the south coast of WA.

By Wednesday, the low will be well-developed over the Bight and a northwest cloudband will extend from South Australia up towards central Australia. Wednesday will be SA’s third consecutive day of widespread rain, which will increase the risk of localised flash flooding, particularly in areas that see thunderstorms.

Image: Forecast accumulated rain during the three days ending at 10 pm AEST on June 17, 2026. Source: Weatherzone.

A surge of powerful winds will also develop over southern WA and possibly parts of SA on Wednesday as the low pressure system deepens over the Bight. This may include damaging wind gusts in some areas, most likely in WA.

Thursday to Sunday: Rain spreading across Australia’s east and southeast

The second half of this week will see rain spreading across parts of the NT, SA, Queensland, NSW, the ACT, Victoria and Tas as the northwest cloudband gradually moves further east.

The northwest cloudband and its associated rainband will remain a prominent feature on Thursday and Friday, causing decent rainfall over a 3,500 km corridor extending from Tas up to the NT.

There is some uncertainty regarding what will happen to the rainband as it moves over eastern Australia over the weekend. While rainfall should ease on Saturday, some computer models indicate that it could become reinvigorated on Sunday or Monday as a low pressure trough deepens over Qld and NSW.

The maps below show how much rain is being predicted over Australia this week by two different computer models. Comparing the maps shows that there is broad model agreement that this week’s rain will be widespread and affect part of every state and territory. However, there is some disagreement about where and how much rain will fall, particularly over eastern Australia.

Image: Forecast accumulated rain during the seven days ending at 10 pm AEST on Sunday, June 21, 2026, according to the ECMWF model. Source: Weatherzone.

Image: Forecast accumulated rain during the seven days ending at 4 am AEST on Monday, June 22, 2026, according to the GFS model. Source: Weatherzone.

This week’s rain has the potential to cause flooding in several states and territories. Check the latest forecasts and warnings in your area throughout the week for the most up-to-date information.