Queenslanders are being urged to be on the lookout for a "wee problem" as a heatwave continues to sweep the state's south.
Acting Health Minister Stirling Hinchliffe says people should be regularly checking the colour of their urine to ensure they stay hydrated.
Mr Hinchliffe delivered the golden advice on Thursday, when the mercury soared to 35.6C in Brisbane and past 40C in many towns in the state's southwest.
"I don't want to be squeamish about this but you need to monitor your own urine," he told reporters.
"If you are feeling that your urine is dark, you should make sure that you increase your fluid intake - that's the best way of making sure you keep yourself safe."
Mr Hinchliffe said he had been briefed about the importance of urine monitoring by the state's chief health officer.
Opposition transport spokesman Scott Emerson agreed people needed to watch their fluid intake when asked whether his counterpart, Mr Hinchliffe, had delivered a bladder blunder.
"People should do everything to make sure they do get enough fluids, (that) they stay out of the heat," Mr Emerson said.
Paramedics responded to 18 heat-related incidents across the state's southeast on Thursday, including 11 where people were hospitalised.
The temperature hit 35.6C in Brisbane just after 1.30pm, six degrees above the average daily maximum for this time of year.
Ipswich sweltered with a top of 37.2C, while the mercury topped 40C in many towns in the state's southwest.
The hottest town was Ballera where the temperature reached 45.4C.
BoM meteorologist Andrew Bufalino said residents across the state's south shouldn't expect any relief overnight.
"It's going to be quite a miserable night," he said.
"(In Brisbane) it's not going to go far below 24C or 25C."
Thargomindah could break the state's January record for highest minimum temperature on Friday morning.
The record stands at 34.5C and a minimum temperature of 33C is forecast for the town in the state's southwest.
"The potential is definitely there," Mr Bufalino said.
Temperatures are expected to return closer to average on Sunday when a trough is expected to bring rain and thunderstorm activity to the state's south.
© AAP 2017