Extreme heat forecast for G20's final day

Queensland's weather will do its best to make G20 leaders uncomfortable on the summit's final day.

Temperatures are expected to reach 40C Brisbane.

It will be even worse west of the city, at Ipswich, where the Bureau of Meteorology is expecting top of 43 degrees tomorrow.

Brisbane is going through what the bureau has called an "extreme heatwave".

Amberley, where President Barack Obama landed on Saturday, hit a top of 43 degrees - the highest temperatures there in almost 50 years.

There'll at least be a reprieve from the humidity on Sunday, with dry and windy conditions expected.

But that's unwelcome news for firefighters, who are battling numerous blazes across the state.

The most serious is a fast moving, out of control fire at Hivesville, west of Gympie, where water bombers are battling to protect homes.

Authorities have warned some property could be lost and have issued a watch and act message for residents to enact plans and prepare.

A second blaze burning near the Darling Downs town of Moonie is also causing concern.

Aerial bombers are also fighting that fire, which is burning 20km east-southeast of Moonie, north of Goondiwindi, on the Queensland/NSW border.

A southeasterly change on Monday is expected to keep temperatures at a still warm 30 degrees before a top of 29 on Tuesday.