Emergency services are mopping up after a series of severe thunderstorms struck Sydney, the Illawarra and Hunter regions, dumping nearly 50mm of rain in just 30 minutes.

Friday night commuters heading home were left stranded from about 6pm as flash flooding in Parramatta and other parts of western Sydney turned intersections to lakes and led several drivers to ask the SES for help.

Shopping centres, hotels and carparks were flooded, cars were forced off the roads leaving people trapped, and flights out of Sydney were delayed by more than two hours as the storms lashed the city.

Nine people were rescued from floodwaters, the SES received 900 calls for help to plug leaky roofs and more than 40,000 properties were without electricity after the storms.

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

Virgin flights on hold and some flights getting cancelled at Sydney Airport pic.twitter.com/LnNpCll4PQ

— Ryan (@rmdarnell) February 8, 2019

Organisers of Sydney’s annual Tropfest short film festival were forced to find another location at the eleventh hour after the wild storms damaged a stage and screens.

The festival will now be held in an alternate location within Parramatta Park on Saturday afternoon.

“While the site we had built in The Crescent at Parramatta Park cannot be used, we are fortunate that Rose Lawn, a safe, suitable location adjacent to the original site will be ready for fans to enjoy today,” event director Paul Kind said in a statement on Saturday.

Lightning happening in Sydney … #sydneystorms pic.twitter.com/NonJyjGNQ3

— Mike C (@mikeculnane) February 8, 2019

The NSW SES warned there was the potential for more severe weather  as thousands of Sydney residents were still without electricity on Saturday morning.

Endeavour Energy on Saturday resumed work to restore power to a remaining 5700 properties which lost power on Friday evening.

“There are nearly 300 electrical hazards needing repairs particularly where trees and large branches have fallen across powerlines,” a statement said.

Streets turn to lakes as massive storms cause chaos across Sydney https://t.co/ZCmeIEhfZv pic.twitter.com/pHOc8GxjdK

— innovativeProvider (@inspiredMichael) February 8, 2019

Endeavour Energy on Saturday said crews had restored supply to over 23,000 customers overnight but extensive repairs were needed to get power safely back to other properties.

Because of the work required, it wasn’t possible to give an accurate estimate of when specific customers would have their electricity restored.

Some 15,000 properties on Ausgrid’s network also went dark in the city’s north and east on Friday.

The NSW Bureau of Meteorology warned warned Sydney residents on Saturday morning they may be in for more storms with temperatures reaching 33 degrees.

Big beast of a cloud drifting over #Sydney CBD as part of a series of #thunderstorms currently impacting parts of #NSW. Several warnings are in place https://t.co/5RC51jfxkG pic.twitter.com/oTTBnEWRNG

— Bureau of Meteorology, New South Wales (@BOM_NSW) February 8, 2019