Commuters are being urged not to drive to work on Wednesday with wild weather and torrential downpours forecast for heavily populated areas of New South Wales.

Airlines are warning travellers from Sydney, Brisbane and the Gold Coast to prepare for significant delays as adverse conditions make flying dangerous and difficult.

Between 70 and 100mm of rain is forecast for Sydney, as much as 150mm in Wollongong and some places could top 200mm as an intense low pressure area zeros in on the cities.

Two months rain could fall in a matter of hours, forecasters have said, with Sydney rivers including the Hawkesbury, Nepean, Cooks and Georges all on flood watch.



While it’s unclear where it will be most intense, the weather system is expected to reach the NSW coast during the Wednesday morning peak.

“We’re asking all road users to perhaps reconsider the need to be on the road through what will be a severe rain event,” NSW Police Chief Inspector Phillip Brooks told reporters on Tuesday.

The overwhelming victims of flood death are people in cars who have attempted to drive through water.

“Drivers, riders, cyclists and pedestrians need to make sure they are safe on our roads.” NSW State Emergency Service Assistant Commissioner Scott Hanckel said parents should think about alternatives for the school drop-off and pick-up and advised businesses to expect workers to arrive late.

“It’s a great day to work from home — if that’s suitable,” he told AAP.

DANGEROUS WIND AND RAIN EVENT

While meteorologists have dramatically upped the rain forecast for New South Wales, in Queensland “wild supercell thunderstorms” could hit the south east of the state on Wednesday while central areas continue to wither under a heatwave stoking bushfires.

“A dangerous rain and wind event is on the way for NSW with Sydney and Wollongong in the firing line with heavy rain, followed by powerful winds as a low pressure system comes in,” said Sky News Weather channel meteorologist Rob Sharpe.

“It’s going to be a vigorous system — short and sharp.”

It had been forecast that Sydney could see up to 50mm of rainfall over a two-day period beginning on Wednesday. Now the Bureau of Meteorology (BOM) is saying as as much as 100mm could bucket down on the city in just a few hours as a concentrated low pressure area heads in.

To put that into perspective, November’s average rainfall in Sydney is 66mm. So the city could see more than a month’s rain in a single day — or even just a few hours.

FLOODING RAINS, DANGEROUS WINDS

And it’s not just Sydney. Wollongong could see as much as 150mm of rain, Nowra 100mm, Katoomba 90mm and Wagga and Canberra 30mm. Some isolated coastal and exposed areas could be walloped with as much as 200mm.

“Current forecasts indicate intense rain could occur in major population centres from Wednesday morning. Damaging winds and hazardous surf conditions are also anticipated,” said the BOM in an alert.

A severe weather warning is in place for the NSW coast from north of Newcastle to south of Nowra and inland to the Southern Highlands and Blue Mountains. But rain, although less of it, can be expected across much of the state.

The culprit is a low pressure system that is expected to enter the northwest of NSW on Tuesday and then track southeast, rapidly intensifying as it crosses the coast about the Greater Sydney area during Wednesday.

Mr Sharpe told news.com.au the severe weather warning for damaging winds was also worth noting.

“The most significant feature of the winds is that they peak after most of the rainfall has arrived. This means that the ground will be soggy and a little bit looser making it easier for trees to come down,” he said.

“This event is likely to lead to flooding, trees and powerlines down and therefore we’ll also have power outages with the worst of the weather.”

Other capitals will be generally dry with just the odd spot of rain in Melbourne. But parts of Queensland could also get a battering.



‘WILD’ THUNDERSTORMS AND BUSHFIRES

Mr Sharpe said there was a chance of wild thunderstorms for parts of southeast Queensland on Wednesday.

“One or two supercell thunderstorms are possible near to the coast around lunchtime on Wednesday, most likely between Bundaberg and the Sunshine Coast, although they cannot be ruled out in Brisbane.

“Those that get hit could be hammered by destructive winds and giant hail.”

Further north in Queensland, they would gladly take some on NSW’s spare rain as the battle continues to dampen down a series of fierce bushfires.

The bushfire emergency in central Queensland could continue for days as fire fighters desperately try to control a huge fire that’s forced hundreds of people from their homes.

A week of high temperatures is forecast for much of the state, leaving firefighters on edge as they try to protect communities near a vast bushfire that’s already scorched 17,000 hectares.

Fire authorities ordered more people out of their homes on Monday, as a Boeing 737 water bomber was brought in from NSW.

The state government declared a disaster situation for communities that have already been hit by fire, or might be in the days ahead.

It means police can forcibly remove residents from the Baffle Creek Catchment, and from Wartburg, Deepwater, Agnes Water, Round Hill, Miriam Vale and Bororen if they refuse orders to leave.

They can also stop residents from returning home until it’s safe. About 100 NSW fire fighters will join the battle on Tuesday, giving exhausted crews who’ve been on the fireground since Friday a chance to rest. Authorities fear the damage bill could soar, but only two homes are confirmed as being lost in the Deepwater area.

As hot, windy conditions roll on, Queensland Fire Commissioner Katarina Carroll warned the fire danger was far from over.

“The next seven days are extremely concerning for us,” she told reporters on Monday.