Beachgoers have been warned surf conditions along the Illawarra coast may be more powerful than they appear on Friday.
The Bureau of Meteorology says conditions will be hazardous for activities like rock fishing and swimming.
The unpredictable surf comes as a rain-bearing weather system arrives in the region on Friday.
Showers and the chance of a thunderstorm are forecast on Friday, most likely from the late morning.
Heavy falls are possible during the afternoon and evening.
Rainfall totals of 30 to 45 millimetres are set to drench Wollongong, according to the bureau.
More rain is forecast on Saturday, with falls of between 8 and 20 millimetres possible in the city.
If those totals eventuate, it would be the city’s wettest spell in more than a month.
The rain should clear by Sunday.