People are being warned to stay away from canals, rivers and reservoirs as Harborough prepares for a mini-heatwave.
The warning is being issued as temperatures are poised to top a 30C (86F) on Friday with the weekend also looking warm.
And it comes after hundreds of people packed into Saddington Reservoir, near Fleckney, at the end of June after months of being locked down.
People were told they were risking their lives as they hurled themselves off rooves into the cold murky waters at the picturesque reservoir.
“Even on hot days the water temperature can be very cold causing muscle cramps and making it difficult for even the strongest swimmers.
“There can also be currents and obstructions under the surface as well as waterborne diseases such as Leptospirosis which can cause blindness or even death,” said the Canal & River Trust.
“People are also known to jump into the water from bridges, locksides or even waterside buildings without knowing how deep the water is.”
Phil Mulligan, the trust’s regional director in the East Midlands, said: “Since lockdown we’ve seen a big increase in people reaping the health benefits of spending time by water, which is fantastic.
“But with temperatures set to rocket we’re urging everyone to please stay out of the water.
“We understand that people want to enjoy themselves.
“But with less of us heading abroad this summer we’ve already seen examples of people getting carried away with a bit of sun and putting themselves in danger.”
He stressed: “We are particularly concerned about reports of people drinking or taking drugs and then jumping into the water to impress their friends.
“It’s a recipe for disaster and people, particularly youngsters and their parents, need to understand that the dangers of what they’re doing are very real.
“Tragically we see cases each year of people getting into difficulty and drowning on our waterways.”
The historic Grand Union Canal also cuts through Harborough and Phil said waterways are “incredible places”.
“But be sensible, stay out of the water and make sure you go home safely at the end of the day,” he urged.
The trust is also exhorting people to observe social distancing guidelines, avoid crowded areas and go to less popular attractions where it’s easier to stay safe.
The Canal & River Trust runs regular campaigns to alert people to the dangers of swimming in inland waterways.
It also has a year-round education programme, Explorers, which helps young people in schools learn how to enjoy their local canal or river safely.
Over 125,000 children over the last four years have benefited from the programme, which focuses on children in Key Stage 2 of the National Curriculum.
To help with water safety education at home the Explorers team has compiled a range of free activities, resources and games which can be found at www.canalrivertrust.org.uk/explorers/learning-from-home/water-safety
To find out more about staying safe near canals and rivers, go to: https://canalrivertrust.org.uk/enjoy-the-waterways/safety-on-our-waterways/summer-water-safety