The fast-moving blaze in bushland at Bundamba, west of Brisbane, was sparked by a house fire which spread to the shipping container just after 11am, with authorities declaring an emergency situation.

Firefighters could not confirm the home was destroyed, but police said the structure was fully involved and two people were treated on scene for heat stress and smoke inhalation.

The blaze was ultimately contained on Saturday night and downgraded to 'advice', with residents now able to return safely home.

Crews remain at the scene monitoring the area and dampening down hotspots.

Smoke from the fire has added to the haze across the southeast, as a southerly change pushes smoke from the NSW fires into the state.

The southeast corner of the state was shrouded in smoke, with the World Health Quality index showing unhealthy levels of air quality across parts of Queensland.

"We have seen a southerly change move up from NSW and with it bringing more smoke from the NSW fires," said Rosa Hoff from the Bureau of Meteorology.

Fire danger in the southeast corner troubled authorities as Brisbane sweltered in 39C heat, with the mercury hitting 40.7C at Amberley near Ipswich.

The hot and dry weather has been unrelenting, but a cool change is expected on Sunday.

"This southerly change means we will see temperatures ease down, however it will still be above average. It is a relief from the severe heatwave conditions, but it still not business as usual.

"Our fire danger ratings will ease back to very high from severe."

Firefighters are pinning their hopes on that cool change for a desperately needed reprieve.

There are more than 40 fires burning across the state. A conservative estimate of 207,000 hectares of land burnt out since the start of the bushfire season is expected to rise, with 22 - possibly rising to 23 - homes lost.

Australian Associated Press