A dust storm that has smothered the Central Coast in a thick red haze is possibly the worst NSW has ever experienced, according to the Bureau of Meterology.

Locals awoke to a blanket of eerie glowing haze covering the Coast this morning after dust swept in from Central Australia.

The dust cloud covers almost the whole of NSW and even parts of southern Queensland, after a strong cold front moved from South Australia and across central and western parts of NSW.

"There was a long preiod of drought in the early 1940s during which time NSW experienced severe dust storms whenever there was high winds," he said.

"But an event like this is extremely rare in that it is so thick and it has covered such a large area.

"This storm is one of the worst we have seen and has closed motorways, halted ferry services and delayed flights."

On top of the haze, wild winds have lashed the Central Coast since early this morning with gusts of up to 100km/h reported.

The extreme conditions caused commuter chaos on the F3 which was blanketed in thick red dust resembling something more like an outback stretch of road.

Health authorities warned people with respiratory illnesses to stay indoors and schools and pre-schools across the Coast also reported an influx of absentees with many parents opting to keep their children at home.

"Dust can affect people with respiratory illnesses, and paramedics are concerned that people with asthma may be affected," Kristie Sky from the Ambulance Service of NSW said.

"We have already seen an increase in calls to people suffering from asthma and other respiratory problems."

NSW Police are urging motorists to slow down and put their lights on due to the extreme dust levels.

"The dust has significantly reduced visability on all roads and I am concerned that drivers are continuing to travel at speeds potentially dangerous in these conditions," Senior Sergeant John Kane said.

"All drivers should slow down until conditions improve."