Health officials recommend entering the water slowly, allowing the body to adjust, and avoiding diving or jumping to minimise putting yourself in danger.
A spokesperson from Public Health Wales said: “Going for a quick dip when the weather is warm is a great way to cool down, but only if it’s done safely.
“The water might look inviting, but it can still be very cold. Jumping straight in can cause an uncontrollable gasp, rapid breathing and a spike in heart rate – putting you in danger within seconds.
“Enter the water slowly; give your body time to adjust; and stay safe while staying cool”.
The reminder comes as temperatures soar across Wales with highs of 30C + expected over the weekend and into next week.
However, the water temperature is still low at this time of year – typically between 15C and 17C – and cold water shock can happen quickly.
