Hunter Valley, Wollongong, and Sydney have suffered from golf ball-sized ice stones that started hammering the roundabouts at about 6 pm local time (7 am GMT) on 20 December.
Social media users have shared photos and videos of the natural disaster showing damaged cars and smashed roofs.
Some of the hailstones looked like pumpkins or flowers, according to users.
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The Bureau of Meteorology has warned that the area remains dangerous, while the Insurance Council of Australia has declared the incident a "catastrophe".
Air Services Australia has reported that planes were not landing at Sydney Airport due to the storms.