What wetsuit thickness for the water temperature?

Dress for the water temperature, then go one step warmer for the wind. A kitesurfer is not immersed like a diver: you stand above the water, in the wind powering your kite, so evaporative cooling does more work on you than on a surfer in the same sea.

Thickness is written as two or three numbers in millimetres, 4/3 or 5/4/3. The first number is the torso panel, thickest for core warmth; the later numbers cover arms and legs. The bands below overlap, because session length, wind strength and tolerance each move you a step.

• Seams matter as much as thickness. Flatlock seams let water through and belong only in warm water. From roughly 17 °C down you want glued and blind-stitched seams; below 14 °C, taped or liquid-sealed seams are what actually keep you warm.
• Fit beats thickness. A loose 5/4 that flushes cold water on every crash is colder than a snug 4/3.
• Drysuits earn their keep when the air and the water are both against you: the usual trigger is wind chill plus water putting you around or below 15 °C / 60 °F effective. You can wear warm layers underneath and change in seconds. They are also baggier and pricier, typically €500–900 in 2026.
• Extremities. Booties, gloves and a hood in 2–3 mm make a startling difference; in properly cold conditions go 5 mm, even 7 mm for boots if you run cold. If you are cold while setting up on the beach, you will never warm up on the water.
• Neoprene tops and hoodies (0.5–2 mm) are the most underrated item in the quiver. Over a shorty or under a summer suit they add a month at each end of the season, and on the beach they kill wind chill while you rig.
• Rash guards and lycra are the number-one item for warm-water riders and beginners: harness rash, board scrapes and sunburn all stop, and a UPF 50 long-sleeve protects more reliably than any cream.

One destination can span most of the chart on its own. The spot page for Zandvoort puts the water at 18 °C in summer and 6 °C in winter: a sealed 3/2 in mid-August, a 6/5/4 or a 5/4 with gloves, 5 mm boots and a hood in late February.

Warm air is no guide either; Essaouira is 20–22 °C in summer under a hot sky and still takes a 3/2. Every spot page carries the summer and winter water temperature and the suit riders there wear.