You still remember August: 24°C water, Lycra or swimwear, and a wetsuit wasn't even a consideration. But September is progressing, the water is starting to lose the degrees it accumulated in summer, and that moment arrives when you come out of a session with purple lips, wondering if it's time to change gear. The answer is almost always yes, but the correct thickness depends on the actual water temperature, not the calendar.
Here's a quick guide to know when to make the switch and what wetsuit thickness you need according to the water temperature in your area.
Approximate thickness guide based on water temperature
- Over 22°C: Lycra or swimwear is sufficient. This is typical in mid-summer along most of the Spanish coast.
- 20-22°C: The change begins to be noticeable. A 2mm neoprene t-shirt or a shorty like the 2/2 short sleeve is the ideal intermediate point.
- 18-20°C: A full long-sleeve wetsuit, 3/2 thickness, is advisable here. This is the quintessential transition thickness in autumn in much of Spain.
- 15-18°C: Time to move up to a 4/3. It's common to reach this range as early as November on the Cantabrian coast, or earlier in more northern areas.
- Below 15°C: This is where winter wetsuits come in, like the 5/3, along with additional accessories for the extremities.
This table is a guide: the perceived temperature also depends on the wind, how long you'll be in the water, and your own cold tolerance. Two people in the same session may need different thicknesses, and neither would be wrong.
3/2 vs 4/3: the difference that truly matters
The numbers indicate the wetsuit thickness in millimeters in different areas of the body: the first is the thickness in the torso (where most protection is needed) and the second in the arms and legs (where most mobility is needed).
- 3/2: 3mm in the torso and 2mm in the extremities. Good balance between warmth and freedom of movement, ideal for transitional waters (approximately 18-20°C).
- 4/3: 4mm in the torso and 3mm in the extremities. More thermal protection at the cost of some flexibility, designed for distinctly cold waters (15-18°C).
The practical rule: if you're torn between the two and you usually surf long sessions, it's better to err on the side of more thickness. Getting cold cuts a session much shorter than a little extra stiffness in the wetsuit.
Signs that it's time to ditch the Lycra
Beyond the exact degrees, your body usually gives you a heads-up before you consult any chart:
- You start shivering before the session ends, not after.
- Your fingers or toes feel numb when you get out of the water.
- You need more time than usual to "warm up" while paddling.
- You cut your session short due to cold rather than fatigue or lack of waves.
If you recognize yourself in two or more of these signs in your last sessions, it's a good time to switch from Lycra to a wetsuit, even if the calendar still says it's "too early."
Not just the suit: protect your extremities too
Hands and feet lose heat much faster than the torso, so even if your wetsuit is adequate, your extremities can still get cold. 3mm booties are a good addition as soon as you start feeling cold feet when you get out of the water, even before increasing the wetsuit's thickness.
Frequently asked questions about when to switch from Lycra to a wetsuit
At what water temperature should you start using a wetsuit?
As a general guideline, below 22°C, the need for a light wetsuit (2mm or 2/2) begins to be felt, although it depends on personal cold tolerance and how long you'll be in the water.
What is the difference between a 3/2 and a 4/3 wetsuit?
The first number indicates the thickness in millimeters in the torso and the second in the extremities. A 3/2 (3mm torso, 2mm extremities) is more flexible and suitable for transitional waters; a 4/3 (4mm torso, 3mm extremities) provides more warmth at the cost of some mobility, designed for colder waters.
How do I know what wetsuit thickness I need?
Be guided by the actual water temperature in your area rather than the calendar date, and keep in mind that factors such as wind or session duration also affect perceived temperature.
Is it necessary to protect hands and feet in addition to the body?
Yes, they usually lose heat faster than the torso. Booties are a good first addition as soon as you notice cold feet, even before changing the thickness of your full suit.
Ready for the change of season? Discover our full range of men's and women's wetsuits and find the thickness you need to continue surfing comfortably this autumn.
