NSW's soggy summer is extending into autumn with significant rainfall driven by La Nina expected across the state.
It has already been a wet week for large parts of NSW but the Bureau of Meteorology predicts more is on the way.
Rainfall that has hovered over the state's northwest will shift east on Wednesday and Thursday, showering the coast, Central Tableland and New England regions.
"Of most concern is some rainfall along the coast, and particularly ... the mid-north coast is going to suffer quite heavily in the next 24 to 48 hours," meteorologist Helen Reid said.
"We do need to be mindful of the sodden river catchments in that part of the world."
Flood watches are current for the Orara, Bellinger and Nambucca rivers, and a severe weather warning has been issued for possible heavy rainfall for the entire mid-north coast district.
Thunderstorms are also possible in state's northwest as the week rolls on, but they will be milder than in recent days.
Rainfall in Sydney will increase over the week, culminating in a very wet weekend, Ms Reid said.
"Catchments further south, including the Hunter and down to Sydney and the Illawarra, we're likely to be having flood watches issued for them as the system evolves."
However, the ACT will cop only a few showers, she said.
Driving the weather is the La Nina oscillation, which generally causes increased rainfall across much of country, cooler days in the south and warmer nights in the north.
"We still have the effects of a lot of moisture feeding into the system and that's just helping us have a wet autumn following on after a wet summer."
