Brisbane sweats through scorcher

Brisbane has sweated through a scorcher, with only cooling sea breezes sparing it from reaching a predicted 41-degree high.

The mercury peaked at 38C during Saturday afternoon in the city's centre.

However, January records were smashed in eight other areas including the southern suburb of Archerfield.

Bureau of Meteorology senior forecaster Pradeep Singh says cooler sea breezes combined with westerly winds generally kept the extreme heat at bay in the river city.

The exception was at Archerfield where the mercury hit 43.5C, just surpassing the highest recorded temperature which was on Australia Day in 1940.

Beaudesert, Nambour, Beaudesert, Toolara, Maroochydore, Redcliffe, Toowoomba and Beerburrum also reached record January highs.

Beerburrum, north of Brisbane, reached 43.1C in the afternoon, smashing the town's 1978 record of 39.5C.

Mr Singh says relief is on the way for those in the state's southeast with cooler temperatures predicted from Sunday.

A high of 33C is expected in Brisbane on Sunday and 36C on Monday.

"But inland areas will still be hot, but not the extreme temperatures we've seen over the last few days," he told AAP.

Mr Singh says the southeast heatwave was caused by a delay in the monsoon season in the state's far north, which pushed warmer winds south.

The Department of Emergency Services said paramedics were kept busy treating 21 patients during Saturday with heat-related illnesses such as exhaustion.