Fire-ravaged Queensland is bracing for searing temperatures up to 40 degrees as exhausted firefighters struggle to contain bushfires burning across the state.

Heatwave conditions are expected to hit the state on Wednesday as hot winds sweep across the southern interior, the weather bureau says.

People were forced to flee the town of Crows Nest, north of Toowoomba, on Monday.

There are fears five homes have been lost but firefighters have so far been unable to complete thorough inspections.

An emergency alert for the fire, which is part of the massive Pechey State Forest blaze, has since been downgraded to watch and act level.

The huge fire has been burning for days, causing severe damage to the water supply for Toowoomba and a dozen surrounding smaller communities.

Residents are restricted to domestic water use only as the council works to repair the network damage with water supply for firefighters the priority.

Toowoomba Region Mayor Paul Antonio is fearful of the weather conditions ahead, saying his community is facing a "massive problem".

About 70 blazes are still burning across the state.

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Queensland Fire and Emergency Services Acting Commissioner Mike Wassing says that with no significant rain forecast to extinguish the fires, the best crews can do is to contain them.

"We've got weeks ahead of us," he's told ABC radio.

"Our planning, from a resourcing perspective across Queensland, is already now projecting out to Christmas and into the new year."

More than 158,000 hectares has been burnt and 16 homes are confirmed lost.

On Moreton Island, a fire is no longer threatening the township of Bulwer.

The blaze continues to burn in the north of the island after forcing campers to flee isolated camp grounds on Sunday.

Authorities continue to watch a cluster of difficult blazes in the Border Ranges region, from Cunninghams Gap and Spicers Gap south to Mount Barney and Mount Lindsay.