The hot weather will affect communities across NSW and the ACT, with the Central West reaching temperatures well above average and experiencing extreme UV ratings.

Weatherzone meteorologist Esteban Abellan said conditions will be extreme over the coming days with temperatures set to reach nine degrees above average.

"A high pressure system over the Tasman Sea coupled with a low pressure trough will bring intense heat over the Central West," he said.

"Conditions will be severe across Friday and Saturday before worsening to extreme from Sunday through to Tuesday."

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Friday will hit 31 degrees with a chance of late thunderstorms and strong winds before the mercury tops 34 and 35 on the weekend.

Monday will heat up further, reaching 37, while people celebrating on Australia Day will stifle through 36 degrees.

Mr Abellan said there should be some relief from the extreme heat at night.

"Normally with these conditions we often see minimums above 20 degrees, so for temperatures to drop to 17 or 18 degrees should provide some relief."

Conditions are set to cool and temperatures drop back towards the average on Wednesday with a 70 per cent chance of rain between one and five millimetres.

The Bathurst summer started with a bang with a 36.8 degree day on December 1, but has been mild overall since then.

January is currently averaging 26.4 degrees compared with the long-term average of 28.4.