Large parts of the east coast remain gripped by heatwave conditions, with the mercury forecast to climb above 40 degrees in some parts today.

The Bureau of Meteorology has issued severe heatwave warnings for a huge expanse of Queensland, including the south-east.

Residents in Brisbane will swelter through a top temperature of 36 degrees today, but in some inland regions it is expected to surge to more than 40 degrees.

The sweltering weather will remain for most of this week, with a minimum overnight temperature in the high 20s offering little relief.

A milder southerly change will bring some relief to eastern parts of Queensland over the weekend.

Similar heatwave conditions are also building over northern parts of NSW.

Areas likely to be impacted over coming hours include Byron Bay, Glen Innes, Inverell, Moree, Murwillumbah and Tweed Heads.

Central Sydney is heading for a top temperature of 35 degrees today, but the mercury will surge to 39 degrees at Penrith in the city’s west.

But other parts of NSW – such as Bourke in the state’s north-west and Dubbo – are forecast to hit 40 degrees or more.

The extreme conditions are not expected to linger, with a cool change sweeping in from this afternoon, bringing the chance of a thunderstorm in the evening.

The bureau said the heatwave was driven by hot dry winds from western and northern Australia.

Fire authorities in Queensland and NSW are warning about an increased fire danger.

Meanwhile, Western Australia is experiencing its third heatwave of the summer, with the Premier Roger Cook insisting the power grid is performing well enough in the sweltering conditions.

Perth’s temperature peaked at more than 40 degrees on Monday, resulting in record power usage.