Central and southern Queensland are sure to swelter this week with temperatures expected to soar over the next four days.
Severe to extreme heatwave conditions are forecast from Wednesday through to Saturday, the Bureau of Meteorology (BOM) says.
It is all due to a trough travelling from the south-west, bringing a hot air mass from central Australia.
Thursday will be the hottest day with 35 degrees Celsius in Brisbane, 38C in Ipswich and 45C in Birdsville.
BOM senior forecaster Sam Campbell said it would be warm overnight too, with a minimum of about 23C in Brisbane but slightly cooler inland.
"It's going to be sunny weather and not much chance of a shower either," he said.
"It's that run of hot days and not getting that relief overnight that leads to heatwave conditions and that's why we are considering this one a heatwave."
Heatwaves are defined as three or more days of high maximum and minimum temperatures that are unusual for the location.
It is calculated using the forecast high and low temperatures over the next three days, comparing this to actual temperatures over the previous 30 days, and then comparing these same three days to the normal temperatures expected for a particular location.
Heatwaves end when the mercury falls to more normal levels.ABC