Thousands of homes across Sydney and the Illawarra remain without power as crews continue to work through complex repairs after an intense burst of thunderstorms overnight.

While a second wave of storms was predicted to batter Sydney again, the Bureau of Meteorology has revised down the likelihood of wild weather on Saturday night.

Endeavour Energy on Saturday said it expects to work into the night to restore power to 2500 customers, with many of them to spend a second night in the dark. “There has been nearly 400 electrical hazards caused by this storm, mainly from trees falling across powerlines in the strong winds,” Endeavour Energy said in a statement.

Nine people were rescued from floodwaters and more than 40,000 properties were without electricity after the wild storms tore through Sydney and the Illawarra and the Hunter regions on Friday night.

Flash flooding in parts of western Sydney turned intersections to lakes and led several drivers to ask the SES for help.

Guildford copped 61 millimetres of rain, including 47mm in just 30 minutes while Sydney Olympic Park received 40mm in the 40 minutes to 7pm.

Parramatta was one of the hardest-hit suburbs, with the majority of outages and calls to the SES coming from the area.

Two schools were badly damaged, with significant repairs needed for roofs at Parramatta East Public School and Parramatta North Public School, an SES spokeswoman said.

Tropfest organisers were forced to find a different location within Parramatta Park for the short film festival after the storms damaged a stage and screens. More than 1000 calls were made to the SES, with roughly half of them resolved by Saturday afternoon, said Vanessa Hutchinson, SES Coordinator Duty Operations. “We’re moving as fast as we can,” Ms Hutchinson told AAP.

“We’ll be working on jobs over the next few days.” Endeavour Energy spokesman Peter Payne said the scale of damage and complexity of repairs meant they could not provide an exact restoration time for all customers.

“There’s a lot of hard work to be done, there’s a lot of damage from this storm,” Mr Payne told AAP.

“We appreciate people’s patience.” Some 15,000 properties on Ausgrid’s network also went dark in the city’s north and east on Friday, but it was expected power would be restored to all by Saturday evening.

Meanwhile, people in the Mid North Coast and parts of the Hunter and North West Slopes have been warned of a severe thunderstorm predicted to bring damaging winds and large hailstones on Saturday night.