Derbyshire Dales District Council has cancelled tonight's Matlock Bath Illuminations due to dangerous conditions.
It is the first time in 18 years the boat parade on the River Derwent has been called off.
A council spokesman said: "Unfortunately the forecasters were right and the river is currently at flood levels and far too dangerous for our boats to parade as planned this evening.
"The boats are the centrepiece of every Illuminations so it is with great regret that we have to cancel tonight's entire event."
They added: "The funfair, which is a fixed attraction, will however be open this evening and entry to the grounds will be free of course, but our advice to any visitors is to stay well clear of the river, which is in flood."
Everyone who has pre-booked tickets for tonight will receive a full refund automatically in the next few days.
The council spokesman said: "Tomorrow is looking more positive. The forecast is for a dry, sunny day, with river levels predicted to reduce.
"We will make a decision at 10am tomorrow on whether the final night of the 2019 Illuminations goes ahead and will make a timely announcement on the Matlock Bath Illuminations Facebook page.
"Our sincere apologies for any inconvenience and thank you for your understanding."