A 3/2mm wetsuit is for water between 14 and 20°C, and a 4/3mm with boots is for 11 to 14°C, so pick the one that matches the coldest water you'll surf. At Flatrock Surf, we reckon a 3/2 is warm enough for winter in Sydney, Perth and the Gold Coast, where winter water averages stay above 18°C, but not for winter in Torquay or Hobart, where the averages drop to around 13°C.
That's the short version. The rest of this guide shows the numbers behind it, where the line falls around Australia, and when it's worth going thicker even where a 3/2 technically does the job.
What's the difference between a 3/2 and a 4/3 wetsuit?
The numbers are millimetres of neoprene. A 3/2 has 3mm through the chest and torso and 2mm through the arms and legs. A 4/3 adds a millimetre everywhere: 4mm through the core and 3mm on the limbs. That extra rubber is warmer, and the trade is that you're paddling against more of it on every stroke.
| 3/2mm steamer | 4/3mm steamer | |
|---|---|---|
| Neoprene (core / arms and legs) | 3mm / 2mm | 4mm / 3mm |
| Water temperature | 14 to 20°C (57 to 68°F) | 11 to 14°C (52 to 57°F) |
| Extras | None needed | Boots |
| Australian winter (Jun to Aug averages) | Sydney, Perth, Margaret River | Torquay, Hobart |
| In our range | Men's 3/2mm Steamer V3 | We don't make one |
Is a 3/2 wetsuit warm enough for winter?
It depends on where your winter is. Going by seatemperature.org's long-term monthly averages, as of spring 2026:
- Sydney: 18.8 to 19.7°C from June to August. A 3/2 is enough all winter, and even September, Sydney's coldest month at 18.6°C, stays inside the 3/2 band.
- Perth: 19.2 to 21.1°C from June to August, then 18.7°C in September and October. A 3/2 covers it.
- Margaret River: 18.3 to 20.1°C from June to August, dropping to 17.6°C in September and October. Still 3/2 water.
- Gold Coast: 21.7 to 22.8°C from June to August. A 3/2 is more than you need; on our chart that's 1.5mm wetsuit top or springsuit water.
- Torquay: 13.3 to 14.4°C from June to August. That's 4/3 and boots territory.
- Hobart: 12.7 to 13.6°C from June to August. A 4/3 with boots, and a step warmer again if you run cold.
So for most of the east and west coast, a good 3/2 is your winter suit. Head down to Victoria or Tassie and it becomes your summer and autumn suit instead. For the season-by-season numbers in each spot, see our guide to which wetsuit thickness is best for Australia.
When should you go a 4/3 even where a 3/2 is enough?
The bands are a starting point, not a rule you're stuck with. Go a step warmer when:
- You run cold. If you're always the first one out of the water, a 4/3 in the bottom half of the 3/2 range is fair enough.
- You're out at first light. A dawn patrol with a cold offshore can feel colder than the water temperature says.
- Your sessions are long. The longer you sit in the lineup, the more those extra millimetres earn their keep.
- The water's right on 14°C. That's the edge of both bands, and the call comes down to the three points above.
The opposite is true too. A 4/3 in 18°C water is more suit than our chart calls for, and once the water's over 20°C, a full steamer of any thickness is more than you need.
What makes a 3/2 warmer without going thicker?
Thickness isn't the only thing keeping you warm. How the suit's built decides how much cold water gets in, and a 3/2 that flushes on every duck dive will feel colder than its rating. These are the features we built into our 3/2mm steamer for exactly that reason:
- Chest zip. A chest zip lets less water in than a back zip, and it leaves the back panel free to stretch when you paddle.
- Glued and blindstitched seams, taped inside. The needle never goes all the way through the neoprene, so there are no holes for water to come through, and the tape seals the inside of every seam.
- Thermal lining. On the V3, a quick-drying stretch terry lining runs from the chest down to the knees.
- Sealed cuffs. Smooth-skin bands close against your wrists and ankles so the suit doesn't flush every time you go under.
Want to know what to check on any suit, ours or not? Our guide on how to tell if a wetsuit is good quality walks through it.
Frequently asked questions
Is a 3/2 wetsuit warm enough for a Sydney winter?
Yes. Flatrock Surf's thickness chart puts Sydney winter in the 3/2 band, because the water averages 18.8 to 19.7°C from June to August according to seatemperature.org, well inside the 14 to 20°C range.
What water temperature is a 4/3 wetsuit for?
Flatrock Surf's chart puts a 4/3mm steamer with boots at 11 to 14°C (52 to 57°F). Below 11°C you'd move to a 5/4mm or thicker with a hood, boots and gloves.
Do I need boots with a 4/3 wetsuit?
Yes. In the 11 to 14°C water a 4/3 is made for, Flatrock Surf's chart pairs it with boots every time, so budget for a pair when you buy the suit.
Can I wear a 4/3 in summer?
Only if your summer water sits below 14°C. On Flatrock Surf's chart, anything from 14 to 20°C is 3/2 water, and above 20°C a 1.5mm wetsuit top or springsuit is enough.
Sources: water temperatures from seatemperature.org (Sydney, Perth, Margaret River, Gold Coast, Torquay, Hobart), checked October 2026. Thickness bands and suit features from our FAQ and product pages.
