At least nine people have died after getting into difficulty in open water during the UK heatwave, charities confirmed, prompting urgent public safety warnings across England and Wales.

Water safety organisations urged swimmers to avoid rivers, reservoirs, and unsupervised coastlines, warning that open water temperatures remain dangerously cold beneath the surface regardless of air temperature.

The deaths — reported at multiple locations — follow a pattern safety charities have recorded in previous UK heatwaves, when rising temperatures drive people toward unguarded water.

Experts warned that cold water shock can incapacitate even strong swimmers within seconds of entry, and that currents and hidden depths make open water far more dangerous than it appears.

Charities called on local authorities to direct the public toward lifeguarded beaches and supervised lido facilities for the remainder of the hot spell.

The heatwave is forecast to continue across much of the UK through the coming days, and safety organisations said they expected further incidents if the public did not heed the warnings.