By Samantha Lock, Holly Hales and Luke Costin in Sydney

Flood levels are continuing to rise across parts of NSW with evacuation orders issued after an overnight deluge broke rainfall records.

Suburbs on Sydney’s fringes are facing the threat of significant flooding after copping more than a month’s rain overnight while a major landslip in the Blue Mountains has left one community cut off.

Premier Chris Minns has called for caution, noting just under 4000 volunteers “spent the night in the cold and windy and rainy conditions, saving people’s lives”.

“While it does look like blue skies across Sydney at the moment and the emergency rain situation seems to be easing… it’s important to note that flood levels in some of the rivers, particularly in Western Sydney are continuing to rise,” he told reporters on Saturday.

In Canberra, the overnight rain is becoming less likely on Saturday afternoon. However, the Bureau of Meteorology says there’s that chance of a thunderstorm, possibly severe.

Eleven urgent evacuation warnings have been issued by the NSW State Emergency Service.

Those living in Windsor, in Sydney’s northwest, as well as parts of Agnes Banks, Sackville, Cumberland Reach and Pitt Town Bottoms have been told to leave.

The North Richmond area is also subject to evacuation orders after moderate flooding in the region prompted the closure of the Richmond and Yarramundi bridges.

In Sydney’s north, residents in Warriewood and Narrabeen have been told to evacuate immediately due to dangerous and rising flooding.

“We have had 152 (flood rescues) across the state, 72 just in the metropolitan area,” SES Commissioner Carlene York said.

Ms York said the agency had so far responded to more than 4000 calls for help, including a car swept into a stormwater drain in Padstow and a train stuck in Bardwell Park.

The Bureau of Meteorology said many areas had been hit with more than 100mm of rain in the past 24 hours with intense falls across the Hunter, the Illawarra, Sydney and the Blue Mountains.

Some areas in western Sydney had more than 200mm with Penrith recording 252mm over the past 48 hours – five times the month’s average.

The Cooks River burst its banks at Earlwood after 7am on Saturday, triggering road closures.

The bureau’s Steven Bernasconi said the situation was easing with heavy rainfall starting to move out into the Tasman Sea.

But flash flooding and landslips remain a concern for Wollongong, the Illawarra and the south coast with two people reportedly taken to hospital after a home at Mt Kiera washed into a creek.

A major flood warning remains for the Hawkesbury, Nepean and Colo rivers while the Georges, Lower Hunter, Myall, Macquarie and Woronora are all on flood watch.

In the Blue Mountains, a landslip on a primary access road left a  community cut off with authorities scrambling to arrange food drops.

“It’s the only access in and out of the valley,” Mike Davis, the owner of nearby vineyard Megalong Creek Estate, told AAP.

“A lot of people are down here camping or in Airbnb’s at the moment so they need to do something fast.”

Warragamba Dam also spilled over just before 6am on Saturday after 100mm of rain fell over the catchment in less than six hours.

A house at Mt Kiera was washed away as flooding hit the area. (Dean Lewins/AAP PHOTOS)

Around 40,000 homes and businesses lost power over the past 24 hours with fallen trees and powerlines further interrupting supply, Ausgrid said in a statement.

Heavy rainfall and possibly severe thunderstorms are also battering southeastern parts of Queensland and are expected to continue into Sunday.

Surfers and other beachgoers were warned to stay “well away from the surf and surf-exposed areas” due to dangerous conditions, particularly at east-facing beaches.