The Illawarra is in for decent rainfall over the next few days, starting today.
Up to 80 millimetres is forecast between now and Friday.
James Taylor from the Bureau of Meteorology said if a thunderstorm eventuates today, rainfall could be varied.
"Certainly a reasonable chance of some half-decent totals, probably less than 10 millimetres but if any thunderstorms move through, it's certainly not out of the question that we could be pushing totals more in the 20 to 30 millimetre range today," he said.
A low pressure system is set to develop off the coast bringing rain and possible storms tomorrow.
Taylor said Friday will be a wash out.
"The south to south easterly flow will wrap moisture around it and bring it back on to the escarpment along the coast and that will generate some more decent rainfall.
"For Wollongong tomorrow we're forecasting the potential of up to 45 millimetres.
"Probably a bit of an easing trend on Friday, more likely less than 20 millimetres but into the weekend definitely easing off," Taylor said.
Wollongong is heading for a top of 19 today with the mercury reaching the low 20s tomorrow and Friday.