Illawarra Rural Fire Service crews are preparing to fight "catastrophic" fire conditions on Tuesday as temperatures are expected to reach 36 degrees Celsius.
Fire crews will be focusing their efforts on Helensburgh, Otford, Stanwell Park, Stanwell Tops and Darkes Forest.
Illawarra district manager Superintendent Greg Wardle said the northern Illawarra suburbs were the "areas with the most extreme fire risk" because they homes were isolated and surrounded by bush.
"All stations will be on standby from 10am," he said.
"Illawarra RFS will move appliances to the Helensburgh area to be on standby so there is a quicker response time.
"RFS will be lifting its level of response.
"For example in normal conditions if there is a bush or grass fire one or two trucks would be sent.
"On Tuesday, five or six crews will be sent.
"Each station will have the maximum capacity of volunteers."
Firefighters will have to deal with high temperatures around 36 degrees Celsius with a relative humidity level of 10 per cent or lower.
Hot winds averaging 50km/h to 70km/h with gusts up to 90km/h are expected.
Supt Wardle said there was "every likelihood we will get fires."
"There is every chance with the temperature and wind conditions that there will be a fire," he said.
"It doesn't take much for a spark to start a fire."
An incident management team will be in palace at the RFS headquarters at Albion Park.
The aviation section is set up to provide plane and helicopter support with water bombing if required.
The "catastrophic" fire warning comes as NSW has been declared a state of emergency for seven days starting on Monday as bushfires rage across the state.
The NSW fires have claimed three lives and so far destroyed more than 150 homes.
It's the first time since new Fire Danger Ratings were introduced in 2009 that catastrophic fire danger has been forecast for the Illawarra.
There is also a total fire ban in place on Monday and Tuesday.
The dangerous conditions on Tuesday comes as 14 Illawarra volunteers head up to Glen Innes to fight the fires on the mid-north coast.
They are the latest in the dozens of firefighters who have travelled to the mid and north coast since September to assist with extinguishing blazes.
Supt Wardle said "the conditions are catastrophic, it does not get worse than that".
The local emergency management committee, which included representatives from RFS, police, Fire and Rescue and support agencies such as council, Ambulance NSW and National Parks and Wildlife Service, were briefed on the fire conditions and planned for Tuesday's fire risk.
What you should do to prepare for fire
Supt Wardle said residents should "take action now".
"Under the expected conditions, fire can change and become uncontrollable," he said.
"Do not rely on a phone call, text or knock at the door because it might not happen in time.
"It is unrealistic to think that a truck can be at every house in the event of a fire.
"To help RFS crews, clean up around your property by removing combustible materials and clean leaf debris from gutters."
Under "catastrophic" conditions, residents are advised that leaving early is the only option.
People should leave bush fire prone areas the night before or early in the day and not to just wait and see what happens.
People should go to a town or shopping centre and plan for if a major arterial road such as the M1 Princes Motorway is closed.
They are advised to make a decision about when to leave, where to go, how to get there and when to return.
"If people decide to stay and defend their homes, make sure there is water and a hose and wear sensible clothing such as jeans, flannelette shirt, enclosed shoes and hat not shorts and thongs," Supt Wardle said.
"Check on your neighbours too especially if they are elderly or disabled.
"Plan with them and do some work to protect their properties."
The RFS community liaison team went to Helensburgh and Otford train stations on Monday afternoon to talk to commuters about the fire situation and what they should do on Tuesday.
"We have known for some time that this year would be an extraordinary fire danger season," he said.
"We have been doing preparations for months to plan for days like Tuesday."
People should stay updated with the Fires Near Me mobile phone app and Rural Fire Service website.
"If you see fire or smoke call Triple 0 not your local fire station," Supt Wardle said.
NSW Health is reminding people to take precautions as smoke from the severe bushfires is expected to cause poor air quality in Sydney and the Illawarra.
NSW Health Director of Environmental Health Dr Richard Broome said smoke can irritate the respiratory system and aggravate existing lung and heart conditions.
"For most people, smoke causes mild symptoms like sore eyes, nose and throat. However, people with existing lung and heart conditions like asthma, emphysema and angina are more likely to be sensitive to the effects of smoke.
"People with these conditions should avoid outdoor physical activity when there's smoke around."
The Salvation Army has launched a Disaster Appeal to support communities affected by the devastating bush fires in New South Wales and Queensland.
Appeal will position the Salvos to help beyond the current support of evacuees and emergency personnel and into the sustained effort required through recovery and rebuilding phases.