Flood watches have been issued between central Queensland and northeast New South Wales as unseasonably heavy rain continues to drench parts of eastern Australia.

A deep layer of moisture-laden east-northeasterly winds interacting with a pair of upper-level low pressure systems is causing widespread rain over eastern Australia. This drenching kicked off on the weekend and will continue during the first half of this week.

Image: Modelled precipitable water and mean sea level pressure on Tuesday morning, showing moisture-laden air being driven over eastern Australia.

Parts of eastern Qld and northeast NSW received more than 100 mm of rain during the 24 hours to 9am on Monday, including:

• 164 mm at Goonengerry, NSW
• 157 mm at Repentance, NSW
• 157 mm at Evans Head, NSW
• 138 mm at Upper Major Creek, Qld
• 116 mm at Ballina Airport, NSW
• 107 mm at Woodlands, Qld
• 103 mm at Haughton Bridge, Qld

For some places, this was the heaviest August rain in decades.

In Qld, Ayr’s 67.8 mm during the 24 hours to 9am on Monday was its heaviest August daily rainfall in 53 years. Townsville Airport’s 67.2 mm was also a 26-year high for an August day.

NSW also had a few places that picked up their best August rain of this century. Evans Head’s 157.4 mm was the site’s highest August daily total since records commenced there in 1998.

Rain will continue to soak a broad area of eastern Australia between Monday and Wednesday under the influence of the twin upper-level lows.

The maps below show how much rain two computer models are predicting over this three-day period, with the heaviest falls expected to occur in central Qld and northeast NSW.

Image: Forecast accumulated rain during the 72 hours ending at 10pm AEST on Wednesday, August 14, 2024, according to the ECMWF-HRES model.

Image: Forecast accumulated rain during the 72 hours ending at 4am AEST on Thursday, August 15, 2024, according to the GFS model.

Some areas of central Qld and northeast NSW could see another 100-200 mm of rain over the next few days, on top of what’s already fallen. A few places might even pick up 200-300 mm, particularly where rainfall is enhanced by local topography or thunderstorms.

Rain will ease over central Qld from Wednesday and most other areas of eastern Australia by Thursday as the upper-level lows weaken and move offshore.

As of midday AEST on Monday, flood watches were in place for parts of central and southeast Qld and northeast NSW. Warnings were also in effect for heavy rain in northeast NSW and hazardous surf in southeast Qld. Be sure to check the latest warnings in Qld and NSW over the next three days.