What wetsuit do I need?
Thickness by month and by stretch of UK coast. Built from the same data on the activity hubs — pulled out so you can answer it in five seconds.
For May on Cornwall (north Atlantic)
5/4/3mm wetsuit
It’ll feel colder on a windy day — if the forecast looks bleak, add a thermal rashie underneath.
Sea temps from Met Office monthly averages · reviewed May 2026
Looking for somewhere to wear it?
View surf spots on this coast →How we got there.
Three things go into the recommendation: the average sea temperature for the month and stretch of coast, the activity (how much of you is in the water), and how you personally handle the cold. Each is a step in a small ladder of thickness bands.
Start with the sea temperature.
We use Met Office monthly sea-surface averages for ten stretches of UK coast. The Cornish north coast in February is not the south coast east of Brighton in February; the table reflects that. The average sea temp for your month and coast maps to a thickness band — the reference is on the right.
Adjust for the activity.
If you’re submerged — surfing, wild swimming — you get the full thickness for the temperature band. If you’re mostly dry — SUP, kayak, where you can usually keep your chest out of the water — we bump one step lighter. You stay warm by moving, not by neoprene.
Then adjust for you.
The same 11°C feels different to different people. I run cold bumps the recommendation one step warmer; I run hot bumps it one step cooler. That’s it — we’re not building a model of your circulation, just letting you nudge the lookup.
Accessories follow the temperature.
Boots come on below 14°C. Gloves below 12°C. Hood below 8°C. These thresholds are conservative on purpose — cold extremities ruin a session faster than a slightly under-spec suit.
The ones we get asked.
Can I get away with one suit all year?
If you’re surfing all four UK seasons, you really need two: a 5/4/3 for autumn through spring, and a 3/2 for the warmest weeks. A single 4/3 covers about eight months reasonably and is cold for two and hot for two — fine if you’re an occasional surfer who doesn’t go out in February.
For SUP and kayak, a 3/2 covers most of the year because you’re not submerged. Skip winter, or layer up underneath.
What if the sea is colder than the monthly average?
It often is, especially in late winter when the sea is at its coldest a month or so after the air. The picker is conservative — we round to the warmer side of each band — but on a day that’s noticeably colder than expected, or after a long northerly blow, treat the recommendation as the floor and add a thermal layer underneath.
Do I need a hooded suit, or just a hood?
A separate neoprene hood is more flexible — you can leave it off on a mild day, or layer it under a beanie. A hooded suit (where the hood is part of the suit) is warmer at the neck join and worth it if you’re mainly a winter surfer, but it’s a more committed buy. For most people in the UK, a 5/4/3 plus a separate 3mm hood is the better answer.
What about a thermal rashie underneath?
Worth it — especially as a way to extend the life of an old suit, or to stretch a 4/3 further into the cold months. A merino or hollow-fibre thermal top under a 4/3 is roughly equivalent to a 5/4/3, with the upside that you can take it off when it warms up in March. Cheaper than a second suit.
Is a 5/3 the same as a 5/4/3?
Close, not identical. The numbers are the neoprene thickness in different panels: torso / extremities, sometimes a third number for legs. A 5/3 is 5mm body and 3mm arms and legs. A 5/4/3 has a 4mm transition panel (usually upper legs) that splits the difference — slightly warmer and slightly more flexible than a plain 5/3. Within one brand’s lineup the difference is small; between brands, fit matters more than the number.
What about kids?
Kids lose heat fast. Treat the recommendation as the minimum and consider going one step warmer, especially for under-tens. Boots and gloves come on earlier than they would for adults. Short sessions, warm car, hot drink waiting — that matters more than another millimetre of neoprene.