More than 15,000 homes remain without power after thunderstorms sweeping through South East Queensland late on Wednesday night brought more than 1.67 million lightning strikes.

Four flights were diverted from Brisbane Airport between 11.30pm and 12.30am overnight, as storms passed directly overhead, and an additional 9500 homes lost power across the region.

A spokesperson for Energy Queensland said 90 per cent of homes that lost electricity in Monday’s storms – which knocked more than 100,000 properties off the grid– had since had power restored.

After three days of afternoon and overnight storms, the weather bureau has again predicted storms for the south-east set to hit later on Thursday amid ongoing severe heatwave conditions in Brisbane.

Senior meteorologist Miriam Bradbury said there would be a storm risk “across most areas” of Queensland, bringing heavy rain and a risk of flash flooding in the north, and for the south-east, damaging winds and hail.

She said Wednesday night’s storms brought wind gusts exceeding 100km/h in southwestern Queensland, including Dalby and Goondiwindi.

“The rainfall was a little bit patchy, but we did see quite a few locations pushing up across 50 millimetres once again,” Bradbury said.

Heatwave conditions were also expected to persist into Friday, with Brisbane to hit 36 degrees on Thursday, although the weather bureau said it would feel like 39.

The weather bureau urged those at risk of heat-related illness to seek shade and cool areas, remain hydrated, and use fans or air-conditioning wherever possible.

Energy Queensland said crews had worked overnight to restore power.

More than 100,000 homes lost power on Monday night, and an additional 12,000 went dark on Tuesday.

Three helicopters were deployed on Tuesday across the worst-affected regions scouting for fresh damage to power infrastructure.

Energy Queensland remained hopeful power would be reconnected to “the majority of customers” by Thursday evening.

On Tuesday afternoon, the Insurance Council of Australia declared a state of catastrophe for SEQ, with more than 16,000 claims received across more than 140 postcodes since Sunday.

By Thursday, Suncorp said it had received 10,000 claims – split evenly between home and motor vehicle cover – from SEQ and northern NSW.

The insurer estimated damages from across the week would cost it at least $350 million.

Suncorp CEO Steve Johnston encouraged people to lodge claims as soon as possible, even before knowing the full extent of damage, so potential damage was assessed as quickly as possible.

Bradbury said temperatures were 3 degrees to 10 degrees above average due to a hot air mass moving over the state, which continued to trigger severe to extreme heatwave warnings for much of Queensland, including Brisbane.

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