Wetsuit Water Temperature Guide

The key to getting the most out of your wetsuit is choosing the right thickness to keep you warm and comfortable without hindering your movement.

What do the numbers on a wetsuit mean?

Wetsuit thickness is usually expressed in millimetres and is represented by two or three numbers. The initial number signifies the thickness of the torso (keeping the body’s core warm), while the second number represents the thickness of the legs and sleeves. For instance, a wetsuit with a 3:2 thickness has a 3mm torso and upper legs, and 2mm arms and lower legs. The thicker torso is crucial for insulation, which keeps the body warm, while the thinner arms and shoulders provide greater flexibility and freedom of movement.

Wetsuits are typically classified by season as the temperature of the water correlates with the seasons. For example, in Western Europe a winter wetsuit would be a 5:4, a spring/autumn wetsuit would be a 4:3 and a summer wetsuit would be a 3:2. In Northern areas of Europe a winter suit would be a 6:5 hooded steamer, while a summer suit might be a 4:3. However, you can also select the ideal wetsuit thickness based solely on the water temperature. Check out the chart below for an approximate guide on which wetsuit thickness to choose for specific water temperatures. Keep in mind that this is only a general recommendation, and additional factors that you can read below may influence your decision.

When choosing a wetsuit thickness, is water temperature the only factor to consider?

Water temperature is undoubtedly a critical factor to consider when selecting a wetsuit, but it isn't the only one. Wind chill, the activity you intend to engage in, your physiology (body mass, your body shape and surface area, percentage body fat, age) your work rate, the time spent in the water and the thermal properties of the wetsuit material are also crucial to take into account. The longer your body stays above water and the more of it that's exposed, the more susceptible you are to the effect of wind and air temperature. If you're into surfing, swimming or bodyboarding, you'll spend most of your time in the water, while windsurfing, kitesurfing, and paddle-boarding will have you mostly out of the water. Consequently, a surfer might prefer a thicker wetsuit in colder water temperatures and warmer air temperatures, whereas a stand-up paddleboarder might opt for a thinner suit under the same conditions. Similarly, a surfer might choose a thinner suit for conditions with warm water temperatures, while a windsurfer might prefer a thicker suit if that location is very windy. Because the nature of swimming involves constant movement, the elevated activity rate increases body temperature and might mean that a swimmer opts for a thinner wetsuit in favour of increased ease of movement.

Therefore, while guidelines can be helpful, finding your own preferences and investing in a range of wetsuits that cater to your needs is crucial if you intend to enjoy water activities all year round.

Reading the temperature guide

As depicted in the chart, wetsuit thickness ranges from 2mm to 6mm. Generally, you'll find yourself using wetsuits that fall in the middle of the spectrum. For instance, a 3mm shortie or steamer is perfect for water temperatures between 18° and 24°C (65° - 75°F) and serves as an ideal high summer suit for the UK and other parts of Europe. During autumn, temperatures may range from 12° to 17°C (55° - 64°F), and you can opt for a wetsuit with a 3mm thickness in the core and 2mm in the arms (3:2) or a 4mm suit in the core and 3mm in the arms (4:3), depending on your sensitivity to the cold and the activity you'll engage in. For temperatures ranging from 11° to 18°C (52° - 64°F), a 4:3 suit is a suitable option, while colder conditions necessitate a 5:4mm suit with a hood, in addition to gloves and boots to keep your feet and hands warm.

For a wetsuit to function as intended it needs to fit well – that means a snug fit all over with good seals at the wrists, ankles, and neck or face (if hooded), without restricting freedom of movement or making breathing challenging or uncomfortable. A close-fitting wetsuit minimises the amount of water inside the wetsuit. There shouldn’t be any loose or baggy areas where water can collect or pool and that may cause water to be “pumped” or circulated around the wetsuit when the user moves. Good seals at the openings reduces the risk of cool or cold water “flushing” into the wetsuit -this loss of heat due to water flow in and out of the suit can have a greater impact on comfort and warmth than the insulating performance of the wetsuit material itself.

What is True Thickness?

Many wetsuit manufacturers measure the thickness of their suits by including the inner and outer jersey layers, which can make the wetsuit appear thicker than it actually is. However, at C-Skins, we proudly state the thickness of the foam rubber alone on all of our wetsuits, providing you with the assurance that you will stay warm and comfortable in the water for longer.

 Wear TheWetsuit That’s Right For You

Please remember that there is are no hard rules about which wetsuit to wear in different water temperatures or conditions. An individual's physical condition, body morphology, rate of work and weather conditions, plus any recent exposure to cold, will influence how long they can tolerate exposure to different temperatures. There will always exist great individual variability in thermal tolerance. The temperatures shown are approximate ranges for comfort for the different thermal performance suit materials and are intended as a guide.