Floodwaters descending on the Central West NSW town of Forbes are expected to peak on Sunday night after the emergency evacuation of 1000 residents.

The Bureau of Meteorology expects the Lachlan River to peak with a highest floodwater level of up to 10.7 metres, as families head to the region for the first weekend of the school holidays.

Slowly rising floodwaters reached 10.64 metres on Sunday morning and an earlier estimated peak of 10.65 metres at midday is expected to be surpassed after accumulative rainfall in the region forced evacuation orders to be issued on Saturday. 

The Bureau reports that major flooding is now occurring at Forbes Iron Bridge, Cottons Weir and Jemalong, where the extent of the flooding is likely to breach August 1990 levels, when 132 properties where inundated. 

The State Emergency Service is warning against complacency after floodwaters began moving in a different direction to that originally predicted. 

The community is well-prepared for floods and has been working with the SES to sure up the town since late August. But while many residents have left the area, the SES warns that it is too late for some residents to seek refuge, with widespread road closures affecting large swathes of the Lachlan River area.

"It isn't behaving like it's previously done, and that's why people are not sure what decisions to make," said Sue Pritchard from the SES.

"We're concerned about the sewerage and other infrastructure failing. People are trying to get to relatives but roads are cut."

Fairfax Media reporter Olivia Grace-Curran, who was evacuated from her home on Saturday, said that the sight of rising floodwaters had driven home the urgency of the situation.

"I can't get to roads where I took photos this morning because they are now completely flooded," she said at 6pm on Saturday.

"People are beginning to see the water enter town, instead of just hearing about it, and are starting to realise this is serious."

On Sunday morning, she added that the town is likely to be cut in two over the course of the day as floodwaters around the Newell Highway rise. 

Five Australian Defence Force trucks have arrived to assist with emergency transport in and around Forbes. 

More than 2280 requests for assistance had been received by the SES by Sunday morning, with the service completing 93 flood rescues.

An evacuation centre has been set up at the local high school, where provisions have also been made for pets. 

NSW Deputy Premier Troy Grant warned the flooding will have a long-term impact on farming communities.

"What's coming is worrying the population more than what will happen tomorrow morning," he told Sky News on Saturday.

The town is no stranger to major flooding events, which have fallen at roughly seven-year intervals over the last century.

Residents of Condobolin, Eubalong, Hillston and Booligal have also been issued with flood warnings and residents are on standby.

Further rainfall is expected in the region later in the week. Ms Pritchard warned that floodwaters are expected to subside slowly and that saturated catchments, full dams and additional rainfall may lead to more flooding in coming days and weeks.