The state’s central and western areas are expected to be impacted the most including in the Riverina, Lower and Upper Western and parts of the Central West Slops and Plains Forecast Districts.
Heavy rainfall could also hit the Sydney metropolitan area.
SES spokesman Greg Nash told the ABC flooding is more probable as many creeks and rivers were already so full.
"This rain will cause additional flood warnings and flooding for rivers and creek systems around NSW," he said.
"So, we want people to be prepared and be aware of their current situation where they are. And if they're travelling around for school holidays to be aware of what's ahead of them.
"We want people to be mindful of the conditions and be aware that what state they leave their house in in the morning may be different to what they come back to when they come home."
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