What is a good temperature for lake swimming? 

Swimming in a lake can be unbelievably refreshing if the temperature is right. You probably won’t know beforehand what the temp of the lake is, so you just have to dip a toe or dive in if you’re a little bit sadistic and get used to it quickly. Some swimmers love to swim in colder temperatures, while some prefer it more balmy and others need it to be much warmer to be the perfect setting for their swim. 

When swimming in open water such as lakes, especially if you go all year round, you will be subjected to a range of temperatures from 0 degrees all the way up to the mid-20s in summer. 

The temperature of the water you’re swimming in will determine how long you can safely stay in the water. Make sure you’re aware of any restrictions at the lake and any safety rules that are in place so you can stay as safe as possible. In this guide, we’ll look at the different temperatures that you may encounter and what is a comfortable water temperature for the majority of open water swimmers, as well as some of the risks that you need to be aware of and some cold water safety tips. 

Guide to cold water temperatures

Different people want different temperatures to swim in, it is entirely personal preference as to how cold or warm a swimmer wants the water to be. The time of year may factor into this and you may get swimmers who are more fair weather, and who only go swimming in open water during the summer months and then the more extreme and experienced swimmers who are more comfortable swimming in cold temperatures. 

0-5 Degrees

Extreme winter swimmers are more than happy with this temperature. It can be painful and could cause you to have shortness of breath as well as go into cold shock. In colder water such as this, it is advised to only stay in the water for a few minutes, get out and warm yourself up slowly to ensure your body temperature doesn’t rise too quickly. 

5-10 Degrees

This is still very cold and you’ll only want to be in it for around 15 minutes, but this is an average water temperature for early Spring in the UK. 

10-15 Degrees

A safe water temperature range for late spring in the UK. Longer swims will be possible although it will still feel very cold and you’ll want to make sure that you are able to increase your core body temperature safely once out of the water.  

15-20 Degrees

For swimmers who are used to indoor heated swimming pools, this will still feel cold, but this is the comfortable range for those who are becoming more experienced with lake swimming. It is cold on initial impact but you will get warmer quicker.  

20-25 Degrees

A rare occurrence in the UK, but it’s not entirely unheard of. Wetsuits are less likely to be seen in these temperatures but swimmers will possibly wear a triathlon suit so they still have a larger area of coverage. This is classed as balmy and is often the ideal temperature for a longer swim. 

If the temperature of the lake is over 25 degrees, it is a good idea to swim with as much caution as you would in cool waters. Wetsuits are not needed and it is highly recommended that you have enough water to drink, you keep an eye on your body heat and you don’t stay in for too long. If the water is over 30 degrees, it is advisable not to even enter the water as there is a very real risk of heat stroke. 

Cold Water Swimming and the Risks

As with anything, cold water swimming comes with certain risks and it is important to understand what your body can go through when you immerse yourself in water that is much colder than you are used to. Cold Water Shock can happen anywhere between 0-10 degrees – wetsuits are advised in these temperatures. A colder water temperature means you should not stay in the water for long periods of time. 

  1. Cold Water Shock – This is the biggest danger for the inexperienced swimmer. The body will automatically defend itself against the sudden change in skin temperature. When entering cold water, you will take in a sharp breath which is often involuntary and it’s your body’s way of defending itself and reminding you to breathe. Your blood pressure may increase as well as your heart rate. Try not to take this breath underwater as that will increase your chances of Cold Water Shock being more of an issue than usual. If you have a heart condition or hypertension then a sudden drop in body temperature can cause issues such as heart failure. Keep your face out of the water and enter slowly to give yourself time to adjust. 
  2. Hypothermia – Another serious risk that you need to be aware of when swimming in lakes. A sudden drop in core body temperature can mean hypothermia, especially if you don’t recognise the signs and get help as soon as possible. This can lead to a loss of consciousness as well as more serious problems with your heart. Learning the limits of how long you can swim will help you, this is based on the water temperature, your physical fitness and your experience. Make sure you always swim with others, you’re dressed appropriately for the water and if you start to shiver or you feel your heart rate slowing down, you get out immediately and warm up. 

What is the body’s response to cold water immersion?

Your body will initially freeze, you’ll take a sharp intake of breath and you’ll want to get moving to warm up. The temperature of cold water can give you a sudden increase of blood pressure but once you get over the short sharp shock and start moving around, you should be fine. In colder water, avoid heat loss by wearing a thicker wetsuit, swimming cap, gloves and socks to make sure that all your extremities are covered. 

Common Questions about Swimming in a Lake

What is the best lake temperature for swimming?

It is all down to personal preference, the time of the year and the weather conditions. Experienced and competitive swimmers are more likely to prefer it colder so they can train their bodies to get used to swimming long distances in the cold, this could be for triathlons or other open water swimming races. For newer swimmers, start out in more moderate temperatures between 10-15 degrees. 

Are lakes colder than the sea?

Yes, inland waters can be much colder than coastal waters. It is important that you know that different bodies of water have a much wider range of temperatures than first thought and just because the air temperature may be warm, does not mean the body of water you’re in will be warm. 

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