Queensland’s bushfire crisis is far from over, with authorities forecasting severe heatwave conditions across the state and police arresting two alleged arsonists.

The Bureau of Meteorology says a severe heatwave that moved in from the state’s north earlier this week is expected to reach the south in coming days.

“Around Capricornia, up around MacKay and inland, it’ll be very hot again, so we’re talking temperatures getting well up into the mid to high 30s for a lot of places, maybe even touching 40 in the odd spot,” meteorologist Rick Threlfall said.

“The hot conditions will persist over the weekend and continue in the fire areas, and in fact spread to many other parts of the state.”

The already extreme temperatures have caused 15 firefighters to develop heat stress, Queensland Fire and Emergency Services Commissioner Katarina Carroll said.

She said crews have been confronted with “unimaginable” conditions.

Thousands of Queenslanders have been forced from their homes as firefighters battle up to 140 wildfires during the unprecedented six-day emergency.

A 27-year-old man was taken into custody for attempting to light a fire at Port Curtis on Friday, while a 26-year-old man was arrested on Thursday for attempting to create a fire in Rockhampton, State Disaster Coordinator Bob Gee said.

Two houses, two cabins and 15 sheds have been destroyed, with a further 14 homes damaged, since the crisis began on Saturday.

“This number could have easily been greater,” Ms Carroll said on Thursday.

“Due to all the proactive work conducted over the last several days, we have lost a minimal amount of houses, thankfully,” she added.

Power supplies have been intermittent in the MacKay region since Monday’s fireball, which is causing problems for residents who use electric water pumps to access groundwater, she said.

“They can’t get to their water, so they can’t defend their property,” Eungella Chalet manager Tess Ford said.

Three blazes of significance continued to burn late on Thursday at Tinnanbar, south of Hervey Bay, Deepwater and North Stradbroke Island.

The small isolated community of Tinnanbar was cut off by bushfire and told to seek shelter as fire bombers and more than 20 fire crews fought the blaze.

Six other towns were ordered to pack up their valuables and evacuate as fires continue to rage in central Queensland.

In the state’s south, a blaze on the eastern side of North Stradbroke Island threatened campers and powerlines.

-with AAP