Tracey Symonds said she was travelling home from a family party in Kiama Heights when flash floods made South Kiama Drive at Hillview Crescent impassable.

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"When the rain hit the windscreen it was like a full force hose," Ms Symonds said. "I had the wipers on the highest setting possible and it just wasn't enough."

Driving through Kiama on Saturday evening, Ms Symonds described water gushing across streets, turning Manning Street, Collins Street and Terralong Street into rivers.

Ms Symonds, who lives in Jamberoo, was attempting to drive home via Jamberoo Road, but found her path blocked.

"I got to Spring Creek and I was aware that there could have been a bit of water but then all of a sudden I got to a wall of water," Ms Symonds said.

"I was a bit shaky when I got out of the car because we had my son and pet dog. It was really frightening. "

Kiama resident Geraldine Flowerdew also found her way blocked when she tried to pick up her daughter's friend after her shift.

"You couldn't get out to South Kiama Drive because it was completely underwater."

Two hours later and the roads were back open, however water levels in the creek that criss-cross Kiama were still high.

"I was rally quite worried about the residents at the entrance of Hillview Crescent, where it's quite low-lying," Ms Flowerdew said.

"You can never normally see the water level, but now it's right up there and all the grasses and the plants are all flattened around it."

Areas of the Illawarra have experienced severe and heavy rainfall overnight, with Kiama recording over 70mm of rainfall in less than two hours.

The State Emergency Service (SES) conducted two rescues overnight and has advised residents to move vehicles undercover and secure loose items around the home.

The SES responded to 33 jobs in the Illawarra overnight, with 30 being in the Kiama LGA.

There were two flood rescues of cars located at South Kiama Drive and Jamberoo Road. Neither car had any occupants inside.

The occupants of a train at Bombo had to be escorted by emergency services off the service at roughly 1am. The train was caught between two landslips on the line caused by the heavy rainfall.

Eighteen passengers were helped off the train by SES, Fire and Rescue, Police and NSW Transport authorities.

In the 24 hours to 9am on Sunday, March 6, Kiama recorded 91mm of rainfall.

The heavy falls continue weeks of wet weather, with the Illawarra expected to experience heavy rainfall and thunderstorms throughout Sunday with the chance of flash flooding.

The Bureau of Meteorology has issued a severe weather warning for the Illawarra and South Coast and expected six-hourly rainfall totals between 70 to 140mm.

A minor to moderate flood warning has been issued for the Illawarra and catchments including St Georges Basin and the Shoalhaven River.

The heaviest rainfalls have been extremely localised. Between bouts of heavy rain, the SES has asked residents to check gutters and drains for blockages to prevent flooding.

The current conditions are also hampering the speed at which emergency services and Councils can respond by closing roads, so the SES has reiterated that if a road is flooded, motorists should not drive through floodwaters.

Motorists are being advised to slow down and exercise caution due to the weather, with particular hazards on Bulli Pass and the Princes Highway south of Kiama.

Ms Flowerdew, who has lived in Kiama for 30 years, and Ms Symonds, who has lived in the area for almost 20 years, both said that the flash flooding was higher and more intense than previous years.

"It all happened within an hour," Ms Symonds said. "It was unbelievable."

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