What Temperature Is Good for Swimming?

If you spend most of your time swimming indoors, you may take the controlled water temperature for granted. Outdoors, the water temperature is often much colder, and if you have your own pool, then you will understand how much water temperature affects your enjoyment of it. But you may ask, what’s the big deal about water temperature? Isn’t water just… water?

Water temperature can affect your body in surprising ways – from the speed of your strokes to the rate of your heartbeat. And while the ideal temperature can vary depending on factors such as the type of swimming (leisure vs competitive) and the swimmers themselves (children, adults, or pregnant women), knowing what’s too hot or too cold is crucial.

What Temperature Is Good for Swimming

In this article, we’ll shed light on common questions related to water temperature such as: Why does the temperature of the water matter? How does it affect my body? What’s the ideal temperature for a refreshing swim, and when does it start being potentially dangerous? Keep reading on to find out the answers.

Why does the temperature of the water matter when swimming?

Water temperature matters when swimming because it can greatly affect your body’s physical response and comfort level. Cold water (<70°F) can lead to hypothermia, a dangerous condition where the body’s core temperature drops below the level required for normal metabolism and body functions. 

Conversely, swimming in water that’s too hot (>90°F) can lead to hyperthermia, a condition characterized by an uncontrolled increase in your body temperature. This could result in dehydration, heatstroke, or exhaustion. Additionally, water temperature can also affect your swimming performance, as your body burns energy to maintain its optimal internal temperature.

What outdoor temperature is good for swimming?

Let’s first clarify the distinction between these two: air temperature refers to how warm or cool the environment outside the water feels, while water temperature is how warm or cool the water itself is.

It’s common to expect that a hot 30°C (86°F) day would mean the water in your nearby pool or beach would be just as toasty. However, this is often not the case, and understanding why this discrepancy exists is key to a safe and enjoyable swim.

Air and water have different heat capacities, which means they absorb and retain heat differently. Water has a higher heat capacity than air, meaning it needs to absorb more heat to increase its temperature.

Conversely, it also means water takes longer to cool down. This principle is why, on a hot day, the water can be significantly cooler than the air around it. It takes longer for the water to absorb and retain the heat, especially if it’s a large body of water like a lake or an ocean.

On the flip side, a cooler evening won’t instantly chill the water in a pool. It takes a while for the water to lose the heat it accumulated during the day, making an evening swim potentially warmer than expected.

So, what does this mean for choosing the best outdoor temperature for swimming? The air temperature is certainly a factor, but you should not base your decision solely on it. On a hot 30°C (86°F) day, the water might still be quite cool, especially in natural bodies of water. Instead, you should rely on water temperature to be a more accurate measure of how comfortable you will feel in the water.

What is the ideal temperature for swimming in a pool?

The ideal pool water temperature largely depends on the swimmer’s activity and personal preference. 

According to the American Red Cross, the recommended water temperature for recreational swimming for adults is between 78 and 82°F (25.5 – 27.8°C). For competitive swimming, slightly cooler temperatures of 77 – 82°F (25 – 28°C) are often used. 

For classes like water aerobics, the water temperature can be a bit warmer, between 82 and 86°F (27.8 – 30°C). For infants and toddlers, warmer temperatures of around 86 – 90°F (30 – 32.2°C) are recommended.

What water temperature is too cold for swimming?

Generally, water is considered cold water at temperatures at or less than 70°F (21.1°C), which may be too cold for most people to swim in without insulating gear. That doesn’t mean the water is too cold to swim in at all, but you must wear a wetsuit to protect yourself from hypothermia.

At water temperatures of 60°F and lower, you can get hypothermia in under 30 minutes if you do not have a wetsuit on. You may even need to wear a drysuit to keep yourself sufficiently warm at those temperatures.

What water temperature is too hot for swimming?

Generally, water temperatures above 90°F (32.2°C) can start to become uncomfortable and potentially dangerous for exercising in due to the risk of overheating and dehydration. However, individual tolerance can vary based on acclimatization, body composition, and personal comfort.

Swimming in natural bodies of water like lakes or oceans is a different experience from a controlled pool environment. Outdoor bodies of water are generally much cooler than indoors, not even accounting for external factors such as wind and rain, and so it is very rare that the water temperature will be too hot outside.

How can hot water affect my body during swimming?

Swimming in hot water can affect your body in several ways. Firstly, it can lead to overheating, which may cause symptoms like dizziness, nausea, rapid heartbeat, and disorientation. 

Prolonged exposure to hot water can also lead to dehydration, as your body sweats to cool itself down, but the sweat does not evaporate in the water to provide a cooling effect.

Additionally, prolonged exposure to high water temperatures can lead to heat exhaustion or heatstroke, which are potentially life-threatening conditions. Heatstroke, in particular, is a serious condition that requires immediate medical attention and can cause damage to your brain, heart, kidneys, and muscles.

How does water temperature affect children or older people differently?

Children and older adults are more susceptible to the effects of extreme water temperatures. Children have a larger surface area relative to their body mass, which means they can lose heat faster than adults. This makes them more vulnerable to hypothermia in cold water. They can also overheat faster in hot water. 

Older adults, on the other hand, often have decreased circulation and can have a harder time regulating their body temperature. This can make them more susceptible to both hypothermia and hyperthermia. Moreover, older individuals might have underlying health conditions like heart disease that can be exacerbated by extreme temperatures.

Is it safe for pregnant women to swim in hot water?

Pregnant women should be cautious when swimming in hot water. High body temperatures, especially during the first trimester, are associated with an increased risk of certain birth defects. 

For this reason, pregnant women are generally advised to avoid hot tubs and heated pools where the temperature is above 100°F (37.8°C). Pregnant women can safely swim in water temperatures that feel comfortable and don’t raise their body temperature too much. They should also stay hydrated and avoid overheating.

What are the signs that the water might be too hot for swimming?

The first signs that the water might be too hot for swimming include feeling overly warm or hot, excessive sweating, dizziness, nausea, fatigue, or a rapid heartbeat.

If you feel too hot while swimming, you should immediately get out of the water to cool down. Find a shaded area if possible, and drink plenty of fluids to rehydrate. Remove any excess swimming gear that may be trapping heat. 

If you feel dizzy, it’s important to sit or lie down to prevent fainting. If symptoms like dizziness, nausea, rapid heartbeat, or disorientation continue, seek medical attention right away.

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