Brighton Swimming Club has cancelled its annual Christmas Day swim, according to the council.
A combination of strong winds and an unusually high tide has been forecast, creating potentially treacherous conditions.
The Brighton and Hove City Council website said that its seafront staff had held talks with the swimming club.
The council website said: “Weather forecasts are predicting tides of 6.4 metres which, combined with strong winds, could result in conditions which are highly dangerous even for the most experienced sea swimmers.
“The decision has been taken because negotiating the heavy shore break will be extremely hazardous.
“Safe entry and exit from the water will be difficult and there is a risk of swimmers being swept back out to sea.
“We would strongly advise everyone not to swim in the sea tomorrow.”
The swim had been due to start just to the west of the Palace Pier at 11am.
A spring high tide of 6.4m is expected at 11.17am – about the time when dozens of swimmers would be in the water.
At the same time winds from the south west are expected to gust up to 35mph.
The city Safety Advisory Group was consulted on Thursday (22 December) and expert advice sought.
Brighton Swimming Club, which has more than 300 members, is Britain’s oldest swimming club and celebrated its 150th anniversary last year.
It was recently awarded nearly £50,000 by the Heritage Lottery Fund to document its history after an archive of old photographs was found.
Brighton Swimming Club members in December last year pictured by Lomokev aka Kevin Meredith.