Emergency crews have worked throughout the night after large parts of the Illawarra were battered by heavy rain and ferocious winds on Thursday.
Severe thunderstorms swept across the region on Thursday evening causing extensive delays on the train lines and leaving hundreds of properties without power.
Almost 20,000 lightning strikes were recorded across the greater Sydney area.
The downpour triggered flash flooding, power outages and more than 600 calls to the State Emergency Service, mostly for fallen trees and damaged and leaking roofs.
More bad weather is forecast for Friday, with rain and possible thunderstorms expected to hang around until early next week.
- with AAP