Residents in flood-affected areas of NSW have been told to prepare to work from home and keep children out of school this week as the state grapples with the severe weather crisis.

NSW Premier Gladys Berejiklian said the rainfall coming this week was “beyond anyone’s expectations” and said up to 4,000 people around the Hawkesbury Valley should be on standby to evacuate.

“And we cannot take our eye off the Mid-North Coast regions, the Hunter regions, they have had sustained rainfall and will continue to have sustained rainfall,” she said.

She described flooding in parts of Western Sydney as a one-in-a-half-century event, and said 16 local government areas, primarily in the north of the state, had been declared a national disaster so far.

NSW State Emergency Service (SES) Commissioner Carlene York said there would be “a number of schools that we advise will be closing”, including in the Mid-North Coast area.

“Going to work, even though you hope it may not be affected, your work premises may be affected in some areas, so once again know that if you do need to go to work make arrangements to work from home,” she said.

“We do not want people on the roads putting themselves at risk, their families at risk, and rescue volunteers attending [at risk].”

Get out now

Some parts of Sydney’s north-west were ordered to evacuate overnight amid a major flooding risk in low-lying areas of the Hawkesbury-Nepean River.

The SES have ordered anyone in low lying areas of Agnes Banks, Pitt Town Bottoms, Pitt Town North, Cornwallis, Gronos Point on the Hawkesbury and low-lying areas of North Richmond to evacuate.

Another order was issued for Freeman’s Reach along the Hawkesbury.

The SES said dangerous flooding is taking place along the Hawkesbury at North Richmond and Windsor.

Flooding has been compared to the February 2020 event, when an east coast low generated more than 500 millimetres of rain over the Hawkesbury-Nepean catchments.

Cranebrook local Priscilla Jones said the river was running “high and fast”.

“The gazebos and playground are mostly under water, the Tench reserve is half under water,” she said. “It is quite scary to watch how fast the water is travelling.”

Emergency volunteers overwhelmed

An SES spokesperson told the ABC they have received around 6,000 calls since the wild weather began late last week.

Statewide there has been a total of 670 flood rescues since Thursday, with 6,700 calls for assistance made.

“We are experiencing a serious, potentially life-threatening weather event at this time, and it will continue to affect a large part of the state for the coming days,” SES’s Assistant Commissioner Dean Storey said.

Mr Storey said 1,500 SES volunteers were working on rescue efforts across the state.

“This is very much a statewide weather event, which requires a statewide response, as I said earlier this is very much in all agencies all government response to this unfolding situation.”

Joanne and Mike Esveld from Bligh Park said they were astounded by the rising water level of the Hawkesbury-Nepean River.

“We’ve been living here for about 30 years and this is the highest we’ve seen it,” Mr Esveld said.

“It’s going to get a lot higher than this, in two or three days it’ll be a lot higher.”

Worse to come

Heavy falls are expected in Western Sydney, Blue Mountains and the Illawarra in the coming days where some areas may receive 200mm.

Evacuation orders at multiple locations on the Mid-North Coast remain in place as Port Macquarie and Taree continue to be inundated by floodwaters.

There will likely be an “explosion or rain and thunderstorms” on Monday and Tuesday as the coastal trough combines with another weather event coming from the tropical north, meteorologist Jonathan Howe said.

NSW Police say they have responded to a range of requests for assistance in the 24 hours to 5:00am, including the rescue of two stranded bushwalkers in the Blue Mountains.

The pair were returning from a camping trip and hiking the Six-Foot Track at Katoomba when they became trapped between a fast-flowing watercourse and a waterfall. Police used a rope system to hoist the hikers to safety.

In another incident, residents of four homes in Wallaroy Crescent in Woollahra needed assistance after a partial wall collapse. A resident noticed a 40-metre natural rock cliff face had shifted after heavy rainfall and contacted emergency services.

On the Mid-North Coast, the search for a missing bodyboarder was delayed due to rough surf.

–ABC