A cyclone watch has been issued for a large stretch of the east coast from Bundaberg in Queensland to Ballina in New South Wales.
Tropical Cyclone Omais about 850 kilometres north-east of Brisbane and is moving towards the city.
However, the category two system is no longer expected to make landfall.
BOM forecaster Michael Knepp said while south-east Queensland may not get the direct impact of the system, severe weather is still on the way.
Gales are expected to develop about southern coastal waters from Friday, and they could reach 90 kilometres per hour or more over the weekend.
Up to 50 millimetres of rain is also predicted for Brisbane and bayside areas this weekend.
A severe weather warning is in place for abnormally high tides and dangerous surf from the town of 1770 to Coolangatta.
Tides and ocean swells are already picking up, drawing surfers and onlookers.
Waves of up to three metres have already been recorded offshore, but could increase to six metres or higher over the weekend, BOM forecaster Lauren Pattie said.
High tides could also exceed the highest tide of the year by a metre on the morning high tides for the next few days.
All Gold Coast beaches and a number of Sunshine Coast beaches have now been closed.
Some holiday-makers have been asked to take precautions after water started inundating the Cotton Tree Caravan Park on the Sunshine Coast on Thursday.
John Ebbels said water started "roaring" through the park about two hours after high tide.
"All of a sudden it was like a tsunami, if you know what I mean," he said, adding they had been asked to move to higher ground.
"It was like a river running through the park. It was pretty full on."
Boat owner Jason Smith had been attempting to sail his boat to Hervey Bay for insurance purposes but he only got halfway before the swell became so big he had to turn around.
"It was pretty rough, very bumpy. I should have been sitting down by now having a beer, but [it was not going] to happen," he said.
"The weather trough came in a couple of hours earlier than I expected it and that was looking at all the weather models.
"Sitting there punching into it at two knots instead of the usual eight knots meant I wouldn't get there until three or four in the morning," Mr Smith said.
BOM said the dangerous surf conditions would likely affect Fraser Island and the coast north of Bargara from Thursday afternoon and evening and the remaining south-east Queensland coast and northern New South Wales overnight into Friday.
Yesterday shark nets were removed and boaties were being urged to seek safe harbour.
Bundaberg Volunteer Marine Rescue skipper Bill Kerr said the rough seas would be too dangerous to rescue people.
"For small recreational boats those winds are dangerous because 40 knots — you have up to 6-metre seas, 35 knots — you have 3-metre seas," he said.
"A small half-metre cab is very, very dangerous and our small rescue boat won't be going out in that.
"Don't go out — it's too dangerous and if the seas are too rough, you'll have nobody to rescue you, and you wouldn't be rescuing your boat."
NASA's Rob Gutro said the space agency's Visible Infrared Imaging Radiometer Suite (VIIRS) revealed Oma has a large eye surrounded by powerful thunderstorms.
He said the US Navy's Joint Typhoon Warning Centre had noted that the "system is struggling to intensify due to the large size of the eye".
"The VIIRS image also showed a long band of thunderstorms wrapping into Oma's low level centre from the southern quadrant, giving the impression of a long tail."ABC