Severe thunderstorms have been developing in the western part of NSW, moving east towards the coast and expected to hit Sydney in the late afternoon or early evening.

Weatherzone senior meteorologist Graeme Brittain??? has warned Sydney residents to prepare for a soaking.

"There will be storms across the eastern part of NSW this afternoon," he said.

"There is a strong chance of damaging winds, hail and flash flooding.

"The storms will move across the Blue Mountains by mid-afternoon and are expected to hit Sydney by 5 or 6pm so it will be a wet trip home for many commuters. People should be prepared and plan for very wet conditions."

The wet weather breaks a lengthy dry spell with Sydney experiencing a record-breaking lack of rain in September and similarly dry conditions in the first part of October until last Friday's soaking.

The Bureau of Meteorology forecasts 5-15 mm of rain will fall on Sydney today with showers to ease tomorrow.

Friday will be a mostly dry day with a few isolated showers, most likely in the morning.

Sunny skies will be back by Saturday with no rain forecast and a top temperature of 26 degrees.

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