There have been flood evacuations as rapidly rising rivers from “record” rain posed a major threat to residents in the NSW Hunter Valley.

The SES door-knocked during Monday night, warning people to leave before it became too dangerous and they could no longer be rescued.

About 60 residents of Dungog and Paterson and people at the Ferndale Caravan Park in the Hunter Valley were urged to evacuate before 11.30pm.

Fresh evacuation orders were issued on Tuesday morning for the Gloucester Caravan Park and parts of Bulahdelah.

More than 30 schools are also closed across the region.

“Over the past 24 hours we’ve seen huge amounts of rainfall — records for a May day to date in some areas,” said SES Chief Superintendent Andrew Cribb.

“Floods move fast and so should you.

“The flash flooding that we’re having from this heavy rainfall is going to occur over the next 48 hours.

“We are expecting lots of isolations, lots of flashing flooding and evacuations.”

Several evacuation centres have been opened, including at the Dungog Memorial RSL Club and Club Gloucester.

The region’s rivers have risen much more rapidly than expected — with days more wild weather on the way.

On Tuesday, there were major flood warnings for the Manning and Gloucester Rivers, and the Paterson and Williams rivers.

NSW SES has advised people to stay indoors due to heavy and intense rainfall and damaging winds at Port Macquarie, Taree, Kempsey, Gloucester, Forster, Seal Rocks, Barrington Tops, Wingham and Yarrowitch.

The Hunter Valley, central coast and mid-north coast copped huge downpours in the 24 hours from 9am Monday.

Port Macquarie received 223 millimetres and Taree had  265 millimetres of rain.

Days of rain lie ahead for parts of eastern NSW with significant flood impacts, damaging winds and large waves.

There had already been more than 20 flood rescues in northern NSW, with at least one person taken to hospital after being rescued from their flood-stricken vehicle.

The SES said it responded to more than 350 calls for help overnight on Sunday.

Of those, most came from the state’s northern region. There were 60 from Sydney relating to fallen trees, blocked roads and property damage.

A severe weather warning for heavy rainfall and damaging winds stretches from the state’s mid-north coast at Kempsey to the Central Coast.

Isolated falls of up to 120 millimetres over six hours are possible, leading to flood watch warnings across the same region.

“We’re already seeing those coastal catchments respond quite quickly to rainfall over the weekend,” NSW SES operational media co-ordinator Emily Barton said.

“With the forecast heavy rainfall over the next few days, we’re anticipating renewed rises and many catchments to reach minor to moderate flooding.

“SES has pre-positioned flood rescue teams, high clearance vehicles and aviation assets throughout the high-risk areas, but we’re urging the community to stay alert.”

Bureau of Meteorology senior meteorologist Angus Hines said a band of rain that formed overnight into Monday was shifting north to the central and northern coastal regions.

Hines called the extended nature of the wet weather “significant” with rain expected to fall in the same region for some days.

“We’re looking at rain for most of the day today, then again tomorrow and then Wednesday, and potentially out towards Thursday,” he said.

“It’s not a short, sharp rain event … it’s a long stretch of maybe moderate rainfall at any one time. But several days in a row of moderate rain will give you big numbers, so we could see well and truly in excess of 200 millimetres.

“Some places will probably get closer to 300 millimetres or 400 millimetres over the course of the entire week.”

Hines said the regions with the highest risk of damaging winds and heavy rainfall were the central, Hunter and mid-north coasts, along with parts of the central and northern ranges.

Dangerous beach conditions are also possible from Sydney’s southern beaches to Seal Rocks, with waves up to five metres possible.

A damaging surf warning has been issued for the coastline stretching from Gosford to Coffs Harbour.

Gusts of about 100km/h are expected over the Hunter and mid-north coast regions.

Widespread minor to moderate flooding is also expected through rivers north of Newcastle and south of Coffs Harbour over the coming days.