Hot and humid weather may sap G20 protesters of their energy

Mother Nature will offer up suffocating humidity and searing heat when world leaders met in Brisbane for the G20 summit.

Temperatures in the city are tipped to reach 35C on Saturday and 36C on Sunday, with sunny and mostly dry days.

But while presidents and prime ministers should be able to enjoy the air-conditioned climate inside the Brisbane convention centre, protesters outside could get hot under the collar.

"Brisbane isn't just about heat, it's about humidity, it saps everything out of you," Queensland a University of Technology criminology expert Associate Professor Mark Lauchs said.

"There's a strong likelihood that people aren't going to want to do anything."

Law enforcement officers may also struggled.

"I actually feel sorry for the cops, who are going to be in riot gear," Prof Lauchs said.

"They're going to be in a lot of strife dressed up that way in the heat over the weekend."

The Bureau of Meteorology has predicted only a 20 per cent chance of a rain shower this weekend.

"It will happen in the afternoon or evening, if at all," forecaster Michael Paech said.

But even if there was rainfall, it won't have any bearing on the temperature peaks in the afternoon.

A G20 "People's March" will coincide with the arrivals of international leaders at the Brisbane Convention and Exhibition Centre, setting off at 11am on Saturday from Brisbane City to Musgrave Park in South Brisbane.

The Australian Federation of Ukrainian Organisations will rally from 1pm in King George Square to protest the presence of Russian President Vladimir Putin in Australia.

Go to 9news.com.au/G20 for all the latest on the summit.