North coast lifeguards are warning of dangerous conditions at the region's beaches as a strong southerly swell moves north.
Many beaches have 'waist deep' signs up today, which warn swimmers not to get out of their depth in the surf.
Coffs Harbour lifeguard Alex Swadling said in the current big swells it's easy for less expert swimmers to get into trouble.
"If it's waist deep only that means conditions are not ideal," he said.
"We're trying to keep members of the public at a safe depth today.
"When we've got waist deep only you've got to make sure you keep your feet on the ground.
"That's going to keep you safe, do not go so far out the back where there could be flash rips on low tide, that sort of carry you out a bit further where you can't touch.
"It has been increasing the swell since this morning, but it's slowly getting bigger and bigger.
"It is a really south swell as well.
"The southern corners are the most protected and the better for surfing, but the northern corners are just getting smashed by the swell at the moment.
"By the looks of things Sydney got all this sort of swell yesterday.
"So it's sort of creeping up the coast and it'll keep pushing up, all the way up to the Clarence probably later on tomorrow morning."
© ABC 2014
16:23 EDT Tropical Cyclone Kate has only caused minor damage on Cocos Islands after passing to the north of the tiny community, more than 2,000 kilometres off the Western Australian coast.