Nurses and wardspeople rushed to find buckets, and lay down blankets and towels to mop up the flooded areas within the ageing hospital's rehabilitation unit.

Gai Watkins said the water on the floor posed a danger to her father, aged 75, who's recovering from open-heart surgery.

She said he and two other patients in the room were transferred to Shellharbour Hospital on Sunday afternoon for their own safety.

"It started on Saturday and got worse on Sunday," she said. "There was water everywhere - coming through the windows, part of the roof.

"It affected my dad's room, and other patients' rooms. The nurses and wardspeople were fantastic, they did everything they could to help.

"But it's clear management needs to take a look at the unit, as the windows look like they've needed fixing for some time.

"As well as the risk of slipping due to water on the floor, it was just really cold and damp which isn't good for people like my father who have breathing difficulties and are trying to rehabilitate after surgery."

Ms Watkins said the wife of another patient took her husband home due to the flooding, with the rest transferred to Shellharbour.

"My father's been in six hospitals over the last six weeks - Shellharbour to Wollongong to St George, back to Wollongong, then to Port Kembla and now back to Shellharbour," she said.

"Port Kembla Hospital definitely needs some maintenance - and now."

Illawarra Shoalhaven Local Health District Executive Director Infrastructure Development Suzanne Harris said staff took immediate action to address the impact of the extreme weather on a number of its health facilities over the weekend.

"Port Kembla Hospital's rehabilitation ward experienced water leakage through some of the windows," she said.

"Staff carried out a risk assessment and temporarily relocated six patients to other areas in the hospital. The district is assessing the damage and planning the appropriate repairs."

Ms Harris said there was also water damage to an operating theatre at Shoalhaven Hospital on the weekend.

"While we carry out necessary repairs, some procedures planned for this week have been rescheduled," she said.

Ms Harris said the district had "rigorous plans" in place to "prevent, prepare for, respond to and recover from any major incident, including severe weather".

"Keeping our patients, staff and visitors safe while minimising disruption to the provision of care remains our top priority," she said.

"We carry out regular inspections on all of our facilities to identify any risks to maintenance and ensure appropriate strategies are in place."