Illawarra residents woke up to a blanket of smoke covering the region's icons on Tuesday, causing the air quality to reach 'hazardous' levels.
The smoke haze lingered for most of the day however a southerly wind change helped ease the heaviness in Wollongong from about 2pm.
The southerly dropped the temperature too.
In the morning, the air particle level was at 477 but dropped to 203 at 2pm.
Air quality across the state was affected by extensive smoke from bushfires, in particular, the Green Wattle Creek, Gospers Mountain and on the mid-North Coast, Northern Rivers and Northern Tablelands regions.
People with heart or lung disease, breathing issues, older adults, and children were advised to avoid exercising outdoors and stay inside.
Everyone else should have reduced prolonged or heavy exertion.
The advice was to rest and use reliever medicine for smoke-related symptoms and if they persisted, seek medical advice.
Some Illawarra school students were forced to stay indoors while parents received updates and were advised to pick up their children from school if worried.
The worst air quality was to the east, south-west and north-west of Sydney and on the Central Coast.
The hot north westerly winds drove down humidity on Tuesday across the Illawarra and created 'severe' bush fire danger conditions.
Firefighters were on high alert for the day and there was a total fire ban in place across the region.
The Bureau of Meteorology reported the the top temperature as 22 degrees in Wollongong but 33 degrees in Albion Park.
Illawarra Rural Fire Service district officer David Bartlett said there had been no reports of fire or crew deployment locally on Tuesday.
However, about 40 volunteers in two strike teams went to Wollondilly to help battle the Green Wattle Creek fire.
The crews were helping with property protection near Oakdale.
"The fire danger level will drop down to 'high' over the coming days with local conditions expected to ease," Mr Bartlett said.
"This will give our volunteers a rest and reprieve. If the weather conditions pick up again then we will re-evaluate.
"Illawarra RFS will still send crews to other regions to help out where they are needed."
The Bureau of Meteorology forecasts top temperatures in the low 20s over coming days with a slight chance of rain.
Smoke haze is also expected to linger.
The predicted thunderstorm on Thursday is on longer forecast.