Heatwaves water safety: staying safe when trying to cool down

When the sun is out, a swim or water-based activity sounds like the perfect way to cool down. The UK has a beautiful coastline as well as inland rivers, lakes and canals and when temperatures rise, many of us head to these open water spots to meet friends, relax and escape the heat.  

But while intentions are good, many people underestimate the dangers of open water.

Why water safety matters during a heatwave? 

Entering the water at any time of the year carries risks, but during hot weather people can fail to consider their safety – until it’s too late. Hot weather doesn’t make open water safer – it increases risk.  

In the UK, there are around five times as many accidental drowning deaths per day when average temperatures exceed 17C compared to cooler days. 

During the record-breaking heatwave over the May Bank Holiday weekend, at least 15 people were reported to have drowned after getting into difficulty in open water. 

This isn’t an isolated pattern. The Royal Life Saving Society UK has identified a clear link between an increase in accidental drownings and periods of extreme or prolonged hot weather, like heatwaves.  

Research into accidental drownings in 2022, a year with three official heatwaves and temperatures reaching 40C for the first time, found that: 

• 46% of accidental drownings happened in the summer months. 
• 19 people died during a single four-day heatwave period in July. 
• 60% of accidental drownings happened inland, away from the coast, most commonly in rivers and lakes. 

Why everyone should care about water safety in hot weather 

In the UK, most drownings don’t happen during organised swimming or events, they are accidents during everyday situations, when risks aren’t fully recognised.  

Even if you have no intention of getting close to any water, it’s important to understand the dangers so you can make safe decisions. 

During a heatwave, risk increases because:  

• More people go near or into water to cool down.  
• Many enter rivers, lakes or reservoirs without proper planning or understanding the risks.  
• Dangers such as cold water shock are often underestimated or unknown 

Common dangers when cooling off 

If you’re planning to swim or take part in water-based activities during a heatwave, understanding the risks can help keep your day safe and enjoyable. 

Cold water shock – even in summer 

Jumping into water during hot weather can be extremely dangerous. One of the biggest risks is cold water shock, which was a factor in two in five outdoor drowning incidents in 2022.   

What is cold water shock?  

Cold water shock is your body’s response to entering cold water (below 15C), which can affect your breathing and movement almost immediately.  

This doesn’t mean just freezing temperatures. Even in heatwaves: 

• UK and Ireland sea temperatures are just 12C 
• Rivers, like the Thames, can be even colder 

The risks:  

• Rapid increase in blood pressure, which can cause heart attacks even in very young people.  
• Gasping, panic and rapid breathing (hyperventilation) increasing the risk of inhaling water, resulting in drowning.   
• A reduction in strength, endurance and muscle making it difficult or impossible to swim (swim failure). 

This can all happen quickly and people can die if they don’t receive immediate medical attention.  

To deal with cold water shock, the RNLI advises:  

• Take a minute. The initial effects of cold-water pass in less than a minute so don’t try to swim straight away. 
• Relax and Float to Live. 
• Keep calm then call for help or swim for safety if you’re able. 

Learn more about cold water shock.  

Unexpected entry into the water 

Even if you aren’t planning to enter the water, the risk is still there. While 57% of people were swimming, 35% of accidental fatalities occurred while the person was walking or running at the time of the incident.  They may have fallen into the water or attempted to rescue someone else in need of help. The danger of entering a body of water should always be considered before reacting to any emergency.  

Inland water risks 

Water safety isn’t just about the coast. 60% of accidental drownings in 2022 happened inland with rivers and lakes accounting for the majority of these incidents.  

The risks: 

• Inland water can appear calm but hide dangers like strong currents. 
• Depth is difficult to judge and can change quickly. 
• These locations are rarely supervised, meaning help may not be immediately available. 

Even if it's a hot day and you want to cool off, don't enter the water unless it's a designated swimming area. 

Alcohol and risk  

Having a drink in the sun is something most people look forward to in the summer, but alcohol significantly increases danger around water. In 2022 1 in 4 deaths were linked to alcohol consumption. 67% of those had fallen into the water unexpectedly. 

The risks:  

• Alcohol reduces awareness and causes slower reactions.  
• It can increase risk-taking behaviour making accidents more likely.  
• It also can impair judgement in an emergency.  

Who is most at risk during a heatwave?  

While anyone can get into difficulty, some groups are at higher risk: 

• Men are significantly more at risk of accidentally drowning, accounting for 83% of victims in 2022.  
• Young people and teenagers are particularly vulnerable. In 2022 40% of accidental drownings involved people aged 13 to 24. 
• Children are increasingly at risk, with 35 deaths in 2022 – a 46% rise compared to the five-year average. 90% of these happened inland.  
• People under the influence of alcohol or drugs.  
• People near water who aren’t going swimming. 34% of accidental deaths in 2022 occurred while walking or running.  
• In land water users. In 2022 60% of drownings happened inland with only 40% at the coast. 

Swimming in a heatwave: simple water safety rules  

You can enjoy swimming and water activities safely during a heatwave by following simple steps: 

1. Respect the water 

When swimming outdoors, cold water and strong currents can be dangerous, even for good swimmers. Always respect the water and do not swim if there are signs saying it's not safe to do so. 

2. Cold temperatures can be dangerous 

Water is much colder than it feels on a hot day. Enter slowly and don’t swim if it feels too cold. Hypothermia is a real risk and usually develops after someone has left the water. Make sure you dry off thoroughly. 

3. Don’t take risks 

If you do go in the water, don't go too far out and stay within your depth. Stay close to the shore or edge, rather than swimming in the middle of open water, so you can get back safely if you need to. Don’t rely on others to help if you get into trouble. 

4. Never swim alone 

Always supervise children and young people near the water. Only swim or paddle in places where there are lifeguards close by. If you're ever open water swimming, never go alone. It's important to take a friend with you in case anything happens. 

5. Avoid alcohol and drugs 

Outdoor swimming and alcohol or drugs don’t mix. If you’re planning on going into or being around open water, avoid alcohol and drugs to ensure you stay safe.  

6. Be prepared 

If you are going swimming always choose a designated swimming area with supervision. Ensure you have a way to call for help and use safety equipment where needed.  

Before entering the water, ask yourself:  

• Is this a safe location? 
• Is it supervised? 
• Do I understand the risks? 
• Do I have a way to call for help? 

What drowning really looks like  

Despite the splashing arms and screaming we've become accustomed to seeing on the big screen, that's not what drowning looks like.  

• Drowning is quiet and quick. You need to be very vigilant to spot the signs that someone who is drowning. 
• A drowning person will alternately dip below the water and briefly back up again. 
• They likely can’t call for help. They will be struggling so hard just to exhale and inhale again. 

We can all contribute to drowning prevention by knowing how to tell when someone is in distress.  

First aid advice for a water emergency

If you are in a situation where someone gets into difficulty in the water learn first aid for drowning so you know what to do in an emergency 

This content was developed with British Red Cross Crisis Response alongside advice and research from the RLNI, and Royal Life Saving Society UK (RLSS).

• Cold water shock
• RLSS UK National Drowning Report UK 2022
• RLSS A headline exploration of the relationship between air temperature and accidental drowning fatalities in the UK