Hundreds of Forbes residents preparing to evacuate as NSW floodwaters rise

Hundreds of residents in Forbes in the NSW Central West are preparing to evacuate as the Lachlan River threatens to flood.

Major flooding is expected on Tuesday night and into Wednesday.

State Emergency Service (SES) volunteers have been going door to door to ensure 800 residents are aware they could be ordered to leave at any time.

Emergency crews have had at least 1500 calls for help, especially for residents keen to get sandbags.

All eyes are on the slowly rising Lachlan River, with two or three times November's total rainfall falling in just days.

"We are assessing and working closely with the Bureau in regards to predictions that may escalate to an evacuation order — when that does occur forewarning will be given to those residents," SES Superintendent Greg Swindle said.

"The community of Forbes is quite resilient they're aware as to what could occur."

Flood levels at Forbes are expected to reach up to 10.65m, similar to those experienced in September 2016 — or even higher.

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Wyangala Dam reached this 104 per cent capacity after rainfall eased.

Residents are advised to check the Bureau of Meteorology website for the latest flood warnings.