5.45pm: The Bureau of Meteorology has cancelled its severe thunderstorm warning for the Illawarra.
The bureau says severe storms are no longer occurring in the region.
However, the chance of a shower or storm remains forecast in Wollongong on Sunday evening.
5.15pm: Illawarra residents are being warned to brace for severe storms, which could bring heavy rain and large hail on Sunday evening.
The Bureau of Meteorology has issued a severe thunderstorm warning for parts of the region, as storms build to the west of Wollongong.
The alert, issued about 5pm, warns storms are likely to produce large hailstones and heavy rainfall, which may lead to flash flooding, over the next several hours.
Locations which may be affected include Wollongong, Bowral, Port Kembla, Albion Park and Kiama, the warning said.
The bureau says a detailed warning will be issued if severe thunderstorms develop in the Greater Wollongong area.
The State Emergency Service (SES) advises that people should move their cars under cover or away from trees, and secure loose items around your house, yard and balcony.
The SES says people should steer clear of creeks and storm drains, and never walk, ride or drive through floodwater.
If you assistance, call the SES on 132 500. In a life-threatening emergency, call triple zero.