The red dust storm that descended on the region in 2009 was exactly eight years ago.
Fairfax Media reported at the time the air conditions were 35 times worse than during a bushfire, the worst the Hunter had recorded.
Flights were grounded because of the visibility. Shipping movements, guided by orange beacons obscured in the eerie haze, ground to a halt.
How it was reported on the day
By Gabriel Wingate-Pearse and Tim Connell
THE dust storm that hit the Hunter about 5.30am today has created the worst air pollultion ever recorded in the region, described as 35 times worse than bushfire conditions.
The poor visibility is continuing to disrupt air traffic and shipping movements, while air quality is hitting asthma sufferers hard, putting pressure on ambulance services to cope with an influx of emergency calls from people with breathing difficulties.
Gale-force wind continues to lash the region with gusts of up to 80 kmh and visibility of 800 metres, after peaking this morning about 8am when winds of up to 90kmh were recorded at Williamtown, and visibility was down to 300 metres.
Between midnight last night and 11am today, the Ambulance Service had received 70 calls from people with breathing difficulties in the northern division, with a spike of about 20 between 7.40am and 8.40am.
95 calls had been received in Sydney, and a total of 250 calls throughout NSW.
Bureau of Meterology duty observer at Williamtown Airport Scott Adams said the massive weather system, affecting areas south of Sydney and up to the north coast, was working its way up the coast, and had yet to hit Ballina.
``For us this is a severe dust storm because we don't normally see them,'' he said.
``It's a huge dust cloud.
It will take several hours before this will clear, it will probably slowly, slowly improve.''
Poor visibility has forced two Jetstar flights which tried to land at Newcastle Airport this morning to go on to the Gold Coast and Brisbane, while a Virgin Blue flight was circling with hopes to land about 9.45am.
Newcastle Airport manager of corporate affairs David Nye said if that plane was forced away it was likely a string of departing flights would then be cancelled due to the flow-on effect.
``If that aircraft gets in that means other aircraft due in a couple of hours may get in,'' Mr Nye said.
``We are now getting to that critical point where those flights which can't get in are due to go out somewhere so we are about to see more flow-on and disruption.
Passengers and their relatives and friends are being advised to check with individual airlines about specific arrivals and departures.
The red haze has also caused delays at the port of Newcastle, with one ship stuck at the dock and another hovering off the coast.
Newcastle Port spokesman Keith Powell said the conditions had made spotting orange navigation beacons much harder, prompting changes to the morning schedule.
The State Emergency Services says it has received 175 requests for assistance statewide, including 13 calls for assistance across the Hunter, mainly for trees toppling over.
All but one of the Hunter jobs have been completed.
The dust is expected to dissipate slowly during the course of the day, but very strong winds are expected to last into the afternoon and evening, easing overnight, with strong winds again tomorrow.
The bizarre weather follows unseasonably warm temperatures and reports of visibility reduced to just 10 metres in Broken Hill.