In short:
Above-average temperatures are expected for south-east and western Queensland during the first weekend of spring.
The weather bureau says the transition between seasons can often bring sudden weather changes.
What's next?
A maximum of 33 degrees is forecast for Brisbane tomorrow, while Birdsville is expected to reach 37 degrees by the weekend.
Unusually warm weather is expected in the coming days for parts of Queensland as the state heats up in the first week of spring.
Multiple coastal cities across the state's south-east are forecast to reach 31 degrees Celsius by tomorrow, according to the Bureau of Meteorology.
"We're expecting the maximum temperatures to be between 4 to 6 degrees above average really across eastern districts," senior meteorologist Sarah Scully said.
"We've got these westerly winds that are pushing much drier conditions and some heat that's built up over the eastern part of the state."
Maximum temperatures for Brisbane could reach 33C by tomorrow, with 30C expected for Bundaberg and the Sunshine Coast and 29C forecast for the Gold Coast.
"The average for Bundaberg at this time of year sits around 25 degrees," Ms Scully said.
She said sudden temperature shifts during seasonal changes were not uncommon.
"Spring is a transition month where it's transitioning from cooler temperatures of winter through to the high temperatures of summer," Ms Scully said.
A reprieve from the heat was not expected until next week, she said.
"We're expecting those warmer temperatures to persist into early next week, with cooler air not expected to arrive until next week."
She said a "settled period of weather" across the state was due to a high pressure system in the east extending a ridge to the mainland.
Birdsville 'very much ready' for hot weekend
Parts of western Queensland are also forecast to swelter, with the weather bureau predicting Birdsville — about 1,500 kilometres west of Brisbane — will reach 37C.
But a warmer-than-average September weekend is not expected to get in the way of the annual Birdsville Races.
Vice president and event organiser Gary Brook said the warmer weather was "part and parcel" of living in the west.
"We're very much ready. We've only recently installed about another 400 square metres of shade on course for our patrons," Mr Brook said.
"For the horses, most of them are camped by the river and a few of them are enjoying swimming the billabong, so keeping them cool and on course.
"We've got all the provisions in place to make sure they're happy and healthy throughout the race days."
Mr Brook said people should take standard precautions when visiting the remote outback town at the weekend.
"When you come to the Birdsville races, you just need to really have both common sense and a sense of humour," he said.
"[Visitors] need to take precautions with hydration and sun protection, but they also need to know that the outback is a place that can throw up in unique situations and you need to be prepared to roll with the punches."
Safety concerns for young and old
Authorities are warning those taking advantage of the warmer weather to follow rules around sun safety.
"My advice for people would definitely be to slap on some sunscreen, put on a hat and stay hydrated," Ms Scully said.
Claudia Wong, the medical director for aged care at Gold Coast Health, also warned the unseasonably high temperatures could be dangerous for older people.
"They're at risk of heat exhaustion or heat stroke, so we ask that people stay inside if they're able to with air-conditioning or a fan and stay hydrated," Dr Wong said.
She said the quick change in daily maximum temperatures had the potential to catch older residents off guard or unprepared.
"A lot of older people are isolated or could be living alone so please make sure you've got neighbours checking in and that sort of thing.
"If people notice symptoms [of heat exhaustion] like lethargy or weakness, please seek medical attention."

