Heavy rain will cause flooding in parts of Tasmania on Wednesday, before a developing low pressure system causes further heavy rain and flooding in parts of New South Wales on Thursday and Friday.

Slow-moving weather patterns causing rain this week

Rain is soaking a broad area of southeastern Australia this week as a slow-moving upper-level low passes over the region, destabilising the atmosphere and creating ideal conditions for rain and thunderstorms.

One reason this weather pattern is producing so much rain is because it is being fed by a steady feed of air from the tropics, which is also being boosted by additional moisture evaporating from the abnormally warm Tasman Sea. This setup is creating a conveyor belt of moisture, also known as an atmospheric river.

Heavy rain targeting Tasmania on Wednesday

Tasmania will experience the result of this atmospheric river on Wednesday as moisture streaming in from the Tasman Sea crashes into the state from the northeast. While this atmospheric river will only make a short pass over Tas, it will still bring enough rain to cause flooding on Wednesday.

Computer models suggest that around 50-100 mm of rain will fall over parts of northeast Tas on Wednesday, with periods of intense rain possibly delivering around 40 to 80 mm in six hours. Isolated heavy falls are also possible in other areas of eastern and southeast Tas on Wednesday.

As of 10am AEST, a severe weather warning had been issued for heavy rainfall in the Furneaux Islands, North East and parts of East Coast Forecast districts. A minor flood warning was also in place for the South Esk River.

Hobart will see rain from this system on Wednesday, although the city should be shielded from the heaviest falls.

Rain to increase over eastern NSW as low develops from Thursday

The upper-level low passing over eastern Australia this week will cause rain and thunderstorms to continue over broad areas of NSW and Qld between Wednesday and Friday. Some of this thunderstorm activity is likely to produce heavy rainfall, which may cause localised flash flooding.

A more focused area of heavy rain is expected to develop over northeastern NSW on Thursday and Friday as a surface-based low pressure system develops off the state’s north coast. This heavy rain will be falling onto a landscape that is already wet from rain earlier in the week, so flooding is a high risk.

While there is still some uncertainty regarding where and how much rain will fall in the coming days, the area most likely to see rainfall that could cause riverine flooding are the Hunter and Mid North Coast districts in NSW. This may change as new forecast model data becomes available over the next few days.

Image: Forecast accumulated rain over southeastern Australia during the 72 hours ending at 10 pm AEST on Friday, May 29, 2026. Source: Weatherzone.

As of 10 am AEST on Wednesday, a flood watch was in place for parts of the Hunter and Mid North Coast districts in NSW.

Sydney and Brisbane will both see a decent amount of rain as this system continues to soak eastern Australia over the next few days. Brisbane’s wettest days will be Thursday and Friday, while Sydney should see rain ramp up on Thursday and continue into Friday based on the low pressure system’s current trajectory.