One of the main organisers Simon Miles said last year was the best ever with around 120 going in the water and record numbers of spectators.
He said that they were hoping as many will get involved this year.
“It is all systems go for this year so far.
“We are looking forward to the event and hopefully the weather will be kind to us.
“Surely it can’t be as cold as it was two years ago when we had ice in the harbour?”
All the safety precautions are in place with St John Ambulance volunteers offering their services for free, a boat, scuba diver and even kayakers on hand to help anyone who gets too cold in the water.
Jane Boulay and members of her musical theatre group will be on hand collecting donations.
Last year the event made around £1,500.
Mr Miles added: “We don’t charge to enter so we get people in the crowd shaking buckets.
“But it is difficult because people are reluctant to donate until they see something happening and it is over so quickly.
“From the starting gun to the end is only about 20 minutes.”
Before the hardy souls are given the signal to leap into the harbour, there’s the fancy dress parade and judging around 11.45am.
There are prizes for the best male, female and junior costume.
People can sign in from 10.30am but Round Table organisers will be making their decision based on weather conditions at 9am.
Mr Miles added: “When we had it on the beach the seascape dictated it far more but it is a lot more sheltered in the harbour.
“If it is slinging it down with rain it is just going to be miserable.
“So we will make a decision on the day and post it on our website and on to Facebook and Twitter.”
Part-time police scenes of crime officer Neil Legg is one of those braving the sea on behalf of dog rescue charity Woodland Farm Kennels.
Mr Legg, 47, of Winterbourne Steepleton, will be dressed as a Dalmatian.
He said: “The charity does such a good job re-homing dogs that have been neglected, lost or abandoned.”
WELLY WANGERS PUT BOOT INTO FUNDRAISING
BRAVE revellers will also be tackling other activities on Christmas Day and Boxing Day in west Dorset.
The annual Charmouth swim takes place at 11am on Christmas Day while the Lyme Lunge is on New Year’s Day.
New for this year is the Welly Wanging Charity Spectacular at the Hive Beach Cafe on Boxing Day from 11am to 1pm.
The event will raise funds for Macmillan Cancer Support and the Bridport Lions. There will be a cash prize for the furthest wang plus a target challenge and children’s best decorated welly competition.
Welly wanging originated in Upperthong, Holmfirth, where the world championships are held every year.
Competitors are required to hurl a Wellington boot as far as possible within boundary lines, from a standing or running start.