The South Coast's weather will take a turn for the worse on Friday when isolated showers are expected but then the wet weather will continue for days.

About 200mm predicted for the Illawarra and it's a similar prediction for the South Coast with Nowra bracing to receive anywhere from 150 to 250mm between Friday and Tuesday.

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As far south as Batemans Bay, residents are warned to expect heavy showers across the weekend and into early next week with about 100mm minimum expected.

Following good drenches in April and May, it's been a surprisingly dry June so far meteorologist Hugh McDowell said.

"Across the Illawarra we've recorded between 5 and 10mm to the 28th day of the month," Mr McDowell said. "A normal June has a mean of 112mm and a median of 81mm, so it has been very dry."

A southerly change on Thursday will bring some rain, which will continue into Friday with about 20mm expected to be widespread across the region.

The worst weather is expected over the weekend when about 160mm of rain is expected to be dumped on Wollongong.

If Saturday's 70mm isn't enough, there's another 90mm predicted for Sunday.

"Sunday will definitely be the worst weather for the Wollongong, Kiama area," Mr McDowell said. "It'll be the wettest of the days."

Southern parts of the region likely to cop up to 100mm of rain on Saturday, with Nowra likely to cop the brunt of the rain.

Further south, Ulladulla is anticipated to see a bit less, but still plenty of rainfall, with Sunday bringing a good drench of 45 to 80mm predicted.

River rises are expected, and Mr McDowell said there was "potential for flooding".

"It's too early to say where the impact will be felt, it's best for people to keep a close eye on the forecast