Meanwhile, SES crews have been kept busy with 20 flood rescues for vehicles and persons stuck on flooded roads. NSW SES crews have responded to more than 1400 incidents across the state.
At Narrabeen Lagoon, an emergency warning was issued at 10:41pm last night as conditions escalated quickly with rapidly rising floodwaters impacting properties.
NSW SES volunteers, supported by local Rural Fire Service members, assisted isolated residents and holidaymakers to relocate to higher ground. An evacuation centre was established at Mona Vale Memorial Hall. Floodwaters at Narrabeen are expected to take several days to recede.
A landslide was also reported at Great Mackerel Beach near the Barrenjoey Headland, impacting three properties. Residents were accommodated nearby locally.
Further north, the communities of Yarramalong and Dooralong have been advised to prepare to isolate for at least 24 to 36 hours due to river rises along the Wyong River and Jilliby Creek.
NSW SES State Duty Commander Sonya Oyston said severe weather impacted parts of the Illawarra, greater Sydney and Hunter regions yesterday afternoon and evening with locally intense rainfall.
"NSW SES crews and our emergency service partners were exceptionally busy last night assisting residents as we saw very high rainfall and dangerous flash flooding," acting Assistant Commissioner Oyston said.
"There has been a lot of flash flooding which has closed roads, and we anticipate some may remain closed for some time.
"We're asking the community to remain patient, and make safe, sensible decisions to never drive into flooded roads."
Rain is expected to persist over the coming days. There is a chance of more thunderstorms today along the coast north of Wollongong.
To stay up to date with the latest information and warnings, download the Hazards Near Me App or visit ses.nsw.gov.au .
