The Queensland Premier said much of the state was in the grips of "unprecedented" heatwave conditions on Monday, which, combined with high humidity and strong winds was making an already tough battle even harder for firefighters.

Premier Annastacia Palaszczuk said the fire had generated flames 10-12 metres high, covered 11,000 hectares and forced the closure of Wartburg State School.

"We expect the fire to turn and head back towards Deepwater and Baffle Creek," she said.

"As this fire is now predictable, containment lines have been established and this has saved some of the houses that were under threat."

A large air tanker and 100 firefighters were also on their way from NSW to help with the out-of-control bushfires.

QFES commissioner Katarina Carroll said more property could be have been lost, with fire crews searching through scorched areas to see if any caravans, boats or vehicles have been destroyed.

As many as 500 properties were under threat on Sunday and similar numbers remained at-risk on Monday, according to Ms Carroll.

Bureau of Meteorology senior forecaster Dave Grant said heatwave records stretching back 20-30 years had been broken as a series of dry westerly winds sweep across the state.

The fires, about 115 kilometres north of Bundaberg, continued to burn overnight and fire crews were still trying to contain the flames, which have forced 300 people to flee.

Queensland Fire and Emergency Services said the bushfire started in Round Hill on Thursday afternoon and by the time it reached Deepwater National Park on Saturday, it had split into two separate fires.

Forty crews battled the Deepwater fire on Sunday and 25 crews were still working to contain the Round Hill fire on Monday morning. Six aircraft were supporting firefighters on the ground.

Waterbombers and reconnaissance aircraft were expected to rejoin the fight on Monday.

Gladstone MP Glenn Butcher said he had met with Agnes Water mayor Matt Burnett and about 300 people had been evacuated so far. QFES said there were 600-800 residents in the evacuation area.

Deepwater residents have been urged evacuate with the "dangerous and unpredictable" fire expected to have a "significant impact" on the community.

Residents should evacuate west towards Miriam Vale using Tableland Road and Fingerboard Road, toward the evacuation point in the Miriam Vale Community Centre.

Round Hill residents remain on standby to evacuate as a second large fire moves north-east through Deepwater National Park.

QFES Inspector Andrew Sturgess said Monday marked the fourth consecutive day of extreme fire danger in central Queensland.

"The very dry winds and extreme heat have seen extreme fire behaviour ... and pushed the fire into the Deepwater community," he said.

"Under some conditions, we can’t suppress the fire and at the peak of the day, all we can do is ensure people are our fire crews are safe and use defensive strategies.

Winds were expected to be 25-30 kilometres per hour on Monday, an improvement on the 40 kilometres per hour gusts on Sunday.

The threat to homes on the outskirts of Agnes Water had been reduced overnight thanks to stronger containment lines and backburning.

Paramedics remained on standby at the scene and had only assessed two people on Sunday for potential smoke inhalation and heat stress.

On Sunday, the out-of-control blaze on the central Queensland coast had already burnt 9000 hectares of land, sending flames 12 metres into the air.

Police declared an emergency situation at 1.45pm and with Premier Annastacia Palaszczuk urged residents in the affected areas to flee.

"We’ve got a very small window of opportunity now for residents to leave so if you are living in those areas of Baffle Creek and Deepwater we really do need you to listen to authorities and please for the sake of your family please listen and please leave," she said.

Ms Palaszczuk said there were 40 wildfires burning across the state on Monday.

- with Ruth McCosker