Sydney has once again been lashed by a massive rain bomb, with 700mm of rain in 24 hours while further north Port Macquarie on the NSW Mid-North Coast has been drenched with 95mm of rain.

Bureau of Meteorology expert Angus Hines said parts of the state were on flood watch.

“It’s been very wet around Tamworth and large parts of NSW, and a lot of that rain is heading into the rivers and the rivers are starting to rise,” Hines told Sunrise viewers on Thursday.

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“It does look like the worst of the flooding is still for later today, into tomorrow, even into the weekend, because it can take a couple of days for the water that falls to reach rivers.

“The Peel River has got a moderate flood warning in place but it’s not expected to reach those moderate flood levels until perhaps tonight or overnight, early into Friday morning.

“People in Tamworth might not look too bad at the moment but be aware those rivers are still climbing over the next 24 hours to 48 hours.”

Hines said conditions were also extremely wet in Sydney, where there was also a risk of floods.

“Sydney is already over four times their monthly rainfall at the moment,” Hines said.

“Sydney’s one area where flooding remains possible today because there’s more rain today.

“The Sydney region got a lot of rain yesterday and overnight, there will be more wet weather today.

“We are currently looking at minor flooding along the Nepean River, to the west. But other parts of Sydney might not even be on rivers but they could see some flooding because water can’t go anywhere, can’t drain into the ground, can’t necessarily flow away.

“So we might see areas of flash-flooding around Sydney today, hopefully pretty isolated, not affecting too many places.

“More broadly across eastern and northern NSW, the spots were flooding could occur is the Northwest Slopes and Plains, Sydney, the Hunter, the Mid-North Coast, the Northern Rivers — those are our districts we’re watching closely.

“Basically all the rivers that flow through all those different districts potentially could see some flooding in the next few days.”

Hines said the weather would likely clear up on Friday.

“We’ll see quite a lot of wet weather today — probably the wettest day of the week for many parts of coastal NSW and a lot of the rain is going to come towards the end of the day today, probably between 4pm or 5pm this evening until midnight,” he said.

“Overnight we will see a real shift in conditions.

“As people wake up tomorrow, maybe a couple of light showers, but certainly the heavier falls will have cleared by about the middle of Friday morning.”

It comes as the hunt intensifies for two men missing after their car was swept into the McDonald river at St Albans, in Sydney’s far northwestern outskirts, overnight amid intense rain fall.

Three men were inside the car which veered off the road about 20km north of Wisemans Ferry.

One man, aged in his 20s, managed to swim to shore. He was taken to hospital.

Emergency crews immediately launched a search but it was soon suspended due to dangerous conditions.

The NRMA has warned drivers to avoid potholes and stop if visibility is severely affected.

“When visibility is so poor that the edges of the road or other vehicles can’t be seen at a safe distance, pull over and wait for the rain to ease off,” it said.

“If you can’t stop at a rest area and the roadside is your only option, pull off as far as possible and wait it out.

“Keep your headlights on and turn on your hazard warning lights to alert other drivers. Be very careful to pick a safe spot to pull over as everyone’s visibility is dramatically reduced.”