Waves of up to 30ft (10m) high have been hitting Devon and Cornwall, prompting fears that inexperienced surfers could put themselves in danger.
It is the result of an Atlantic depression combining with winds gusting up to 70mph (110k/hr).
Waves at Portreath in Cornwall washed away a 100-year-old stone hut on the breakwater on Monday.
A search for 18-year-old Harry Martin from Newton Ferrers, who has been missing since Thursday, has continued.
Police, the Dartmoor Rescue Group, coastguards and members of the public have taken part in the search since the teenager disappeared.
Mr Martin, who was taking photographs of stormy seas, was last seen by his father leaving his home and walking towards a coastal path on Thursday lunchtime.
Costs 'will rise'
Dave Owens, the assistant head of service for the environment at Cornwall Council, said: "At the moment with the damage we know that has happened to date we're up to about £1.5m. That is only going to go higher.
"That doesn't include anything on the coast path yet. We will probably get collapses as a consequence of this weather, for probably around 12 months."
The harbourmaster at Newquay said so much sand had been lost from the harbour it had exposed a boat wreck never seen before.
Graham Alecock-Smith said: "We've got some guys who have been in town for 60 years but nobody recalls seeing it before.
"I had a chat with Newquay Old Cornwall Society. They have no knowledge of it either, but think it may be an old crabbing boat."
The boat will be removed on Tuesday for health and safety reasons, Mr Alecock-Smith confirmed.
Waves of up to 27ft (8m) have been recorded off Land's End, Cornwall.
A police officer has spoken about how he rescued a man from heavy surf in Cornwall.
Sgt Reg Butler of Devon and Cornwall Police pulled the man to safety at 03:00 GMT on Saturday morning in treacherous conditions.
Officers secured a line to Sgt Butler, who waded out to pull the man to shore at Towan beach in Newquay.
Sgt Butler said "another 30 seconds" and the man could have been washed out to sea.
On the Isles of Scilly the quay on St Mary's has been closed because of large waves.
Harbourmaster Dale Clarke said: "It's just astonishing to see the power of the sea and how high it's actually getting here."
On Sunday, the county's fire and rescue service said it had attended "several flooding incidents" including in Perranporth where crews cleared 2ft (0.5m) of water from Tywarnhayle Square.
In Seaton the sea has damaged part of the beach cafe and part of a seawall has collapsed following high tides and large waves.
Some public transport has been affected. First Great Western has warned passengers there is a risk to services in Cornwall, Devon, Somerset, Wiltshire and Dorset.
The Met Office has issued yellow "be prepared" warnings for south-west England and said there was a risk of coastal flooding and large waves.
Surfing website Magic Seaweed said it could be a "step into the unknown" as people prepared to surf the Atlantic "code red" storm at its peak intensity.
The Maritime and Coastguard Agency and Devon and Cornwall Police said while they could not stop people going into the water, they urged them not to put themselves or others in danger.
"They really need to think carefully about the conditions and about their own abilities," an agency spokesman from Falmouth Coastguard said.
"If they're in any doubt at all, then I'd say, 'please don't do it'."
Last October, Devon surfer Andrew Cotton, from Braunton, hit the headlines when he surfed a 100ft (30m) wave off Nazare beach in Portugal.
Mr Cotton said he intended to ride the surf off Ireland, but will do so only if he believed it was safe.
"My advice would be not to go out alone and to be realistic about your ability," he told BBC News.
"Know your limits. The sea is so powerful and demands the utmost respect."
"Knowing when to call it quits can make the difference between surfing again tomorrow or never surfing again," he added.
Laurence Couch a surfing instructor in Cornwall with 40 years experience, said he hoped to surf off St Ives Bay, but would wait to see what conditions were like.
"These are rogue waves - real monsters - so I'm looking forward to it, but I'll be looking for a more sheltered area to surf.
"If you're not really experienced, my advice is simple - stay out the water," the 51-year-old from Hayle said.