Heatwave warning for large parts of eastern Australia, temperatures to hit 40 degrees or more in some parts

Millions of Sydney residents are set to endure sweltering temperatures from today as a heatwave grips large parts of eastern Australia.

The mercury is forecast to climb up to 36 degrees in Penrith and 34 degrees in Liverpool in western Sydney.

But northern New South Wales and parts of western Queensland are expected to bear the brunt of the scorching weather, with daytime temperatures set to reach 40 degrees in some communities.

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The Bureau of Meteorology has issued a severe heatwave warning for NSW locations including Armidale, Camden, Campbelltown, Hornsby, Liverpool, Moree, Nowra, Orange, Richmond and Wollongong.

In Queensland, the bureau says the heatwave is forecast to impact Bowen, Birdsville, Barcaldine, Cloncurry, Gladstone, Longreach, Mackay, Mount Isa, and Roma.

Children, pregnant women and the elderly are being advised to take extra care and to be aware for symptoms of heat exhaustion and heat stroke.

Fire authorities in NSW and Queensland are urging people who live or are visiting bushfire-prone areas to know the fire danger rating and have a plan of action in case a bush or grass fire threatens.

And motorists are being asked to keep calm and avoid feeling frustrated if road delays occur.

The bureau says the scorching conditions will remain until Saturday when cooler conditions kick in.