Sydneysiders heading out on Friday night may expect rain to dampen their night as severe storms close in.

Western Sydney is likely to "cop the worst" of the storm in the late afternoon or early evening, and residents can expect to see damaging winds, large hailstones and heavy rainfall that may lead to flash flooding, Weatherzone meteorologist Craig McIntosh said.

It is unclear if Sydney's coastal areas will experience a storm with the same intensity as the one in western Sydney, but there is a "good chance the Sydney basin will get some showers," he said.

A NSW State Emergency Service spokeswoman said crews and additional volunteers were on standby for "the wild weather across NSW, including Sydney".

"Take precautions by moving cars under cover and away from trees, secure and put away loose items and don’t drive through flash flooding areas," she said.