The southerly will drop temperatures as it passes through and will ease the high smoke levels experienced in the region.

A thick blanket of smoke made air quality reach 'hazardous' levels on Tuesday morning and has continued into the afternoon.

The particle level was at 477 but dropped to 203 at 2pm.

Read more: What to expect for Tuesday's 'severe' fire danger in Illawarra

Firefighters are prepared to tackle any fires that start. There is a total fire is also in place across the region.

People with heart or lung disease, breathing issues, older adults, and children should avoid exercising outdoors and stay inside.

Everyone else should reduce prolonged or heavy exertion.

The advice is to rest and use reliever medicine if you get smoke-related symptoms and if they persist, seek medical advice.

The smoke is expected to linger until later in the day.

The worst air quality is in east, south-west Sydney, north-west Sydney and the Central Coast.

Air quality across the state is affected by extensive smoke from bushfires, in particular, the mid-North Coast, Northern Rivers and Northern Tablelands regions.

Hot north westerly winds were expected to drive humidity on Tuesday across the Illawarra and created 'severe' bush fire danger conditions.

The Bureau of Meteorology says the top temperature will be 22 degrees in Wollongong but 33 degrees in Albion Park.

On Monday, the bureau reported a maximum temperature of 33 degrees.

NSW Rural Fire service is asking people to be vigilant and to call triple zero immediately if they see a fire without a fire truck in attendance.

Some Illawarra RFS crews are helping to fight the Green Wattle Creek fire in Wollondilly.