The Christmas Day dip at Cheltenham's lido has been cancelled because of the harsh weather conditions for what is believed to be the first time ever.
In previous years between 60 and 80 people have turned out to swim in the freezing waters after signing a waiver form that they understand the risks to health involved in such swims.
Managers said the pool is covered by thick ice and to try to break it may damage some of the lido's structure.
Julie Sargent, chief executive of Sandford Parks Lido, said "we've got to protect its 75-year-old engineering".
Ms Sargent added they feared that with the ice being so thick it would take an extremely hard impact to break it which could shatter "the historic scum channels".
The tradition dates back to 1942 when US troops who were based at the lido decided to take a yuletide plunge. Regulars have continued the practice ever since.
There are also health and safety concerns due to frozen pipes.
"Our pipework with our filters is original 1935 engineering and our insurance for the Christmas Day swim states that we have to have the water flowing with chemicals," added Ms Sargent.
"If we had a thin layer of ice we could still achieve that but we have pipework which is external to our plant room that is frozen solid which makes it impossible to start the filters."
Ron Coltman, director of the lido said he was "upset" it would not be used this Christmas, and added: "If there was an accident nobody would ever forgive us and we would never forgive ourselves."