Surf Forecasts:
Cat Bay (Shelly Beach) surf forecast from 12 Sep 2026:
- Best quality surf: Thursday 17 Sep, 10AM (local time) - 7ft (2.1m), 14s period, SW swell with cross-offshore winds.
- Most powerful swell: Tuesday 15 Sep, 10PM (local time) - 11ft (3.5m), 14s period, SW swell with 4,616 kJ wave energy.
- Next surfable swell (1★+): Thursday 17 Sep, 10AM (local time) - 7ft (2.1m), 14s period with SW swell.
Best Forecast Surf Conditions for Cat Bay (Shelly Beach) this week:
The surf forecast for Cat Bay (Shelly Beach) over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Thursday (Sep 17) at 10AM. The primary swell is predicted to be 2.1m and 14s period. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Cat Bay (Shelly Beach) in the next 16 days are 3.5m 14s and forecast to arrive on Tuesday (Sep 15) at 10PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.3m 6s period and expected on Wednesday (Sep 16) at 10PM.
| Wave Type | Time (AEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 10AM (Thu 17th Sep) | 7ft (2.1m) 14s |
| Best Surf | 10AM (Thu 17th Sep) | 7ft (2.1m) 14s |
| Most Powerful | 10PM (Tue 15th Sep) | 11ft (3.5m) 14s |
Table - best surf conditions forecast for Cat Bay (Shelly Beach) over the next 16 days.
The Lowdown
Righto, surfers, Rusty here with the lowdown on what’s cookin’ for the next couple weeks at Cat Bay (Shelly Beach). The setup for this place is sheltered, so it needs a decent south-west push to really get going.
Let’s be honest, the first few days are a bit of a write-off for decent waves. We get a fun pulse of solid, long-period groundswell on Saturday the 12th – 7ft of SW swell with a deep 15-second period. That’s proper energy (2026), and the water’s sitting at 57°, which is about average for this time of year. With a light SE breeze keeping it clean, it’s a great call for experienced surfers. Go have a crack.
Then it goes to custard. Sunday and Monday are all onshore junk. Tuesday the 15th gets a hefty 8ft to 12ft of swell, but with howling winds – 25 to 31 mph – it’s gonna be a washing machine. Honestly, that’s more a kite session than a paddle. Wednesday the 16th has a massive 10ft swell, but the wind is howling and conditions are messy. There’s a gap right up to Thursday the 17th where things tidy up. The morning of the 17th, it's 7ft of SW swell with a light cross-offshore breeze – that’s clean and surfable.
Then we get another flat spell. There’s a big, promising run right at the end of the window. Wednesday the 23rd afternoon is a standout. Swell holding at 8ft from the SW, long 15-second period, and a light ESE cross-offshore breeze. That is a classic clean, powerful afternoon. The following day (Thursday the 24th) is ruined by onshore winds again, but then Friday the 25th afternoon is the gem of the whole forecast. We’ve got 4ft of very long-period SW groundswell (19 seconds, 2209 energy) and glassy conditions. That’s a long-period groundswell at a beach-break, but with that kind of power and zero wind, it’ll hold up well. The weekend of the 26th and 27th sees a consistent run of clean 5ft to 7ft SW swell with light offshores or even glass. Good to excellent right through.
In summary: Saturday the 12th is a solid pick, but your absolute can’t-miss window is Friday the 25th afternoon through Sunday the 27th. The glassy conditions and the quality of the long-period groundswell on the 25th will be something special. Be ready for it.
Rusty.
Short Range ForecastLight rain (total 4mm), mostly falling on Mon morning. Warm (max 21°C on Sun afternoon, min 10°C on Tue morning). Winds increasing (light winds from the SE on Sat afternoon, strong winds from the SW by Tue morning). | Days 5-7 Weather SummarySome drizzle, heaviest during Tue afternoon. Very mild (max 15°C on Fri morning, min 8°C on Thu night). Winds decreasing (strong winds from the SW on Tue afternoon, light winds from the W by Thu night). | |||||||||||||||||||
Sat 12 | Sunday 13 | Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | ||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Swell Height Map |  |  |  |  |  |  |  | |||||||||||||
Wave Height (m) Direction Period (s) | SW 15 | SW 15 | SW 14 | SW 15 | SW 15 | SW 14 | SW 13 | SW 13 | SW 13 | SW 14 | SW 14 | SW 15 | SW 15 | SW 15 | SW 14 | SW 14 | SW 13 | SW 14 | SW 17 | SW 15 |
Wave Graph  | ||||||||||||||||||||
 kJ | 1882 | 1381 | 1006 | 927 | 606 | 357 | 257 | 130 | 2426 | 3809 | 4308 | 3883 | 3444 | 2830 | 1830 | 1262 | 852 | 801 | 725 | 1765 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross-on | on | on | cross-on | on | cross-off | cross | cross | cross-off | cross-off | off | cross-off | cross-off | cross-off | cross-off | cross-on | on | cross-on | on |
High Tide | 00:42AM2.17m | 1:04PM2.24m | 1:37AM2.28m | 1:46PM2.28m | 2:25AM2.36m | 2:26PM2.30m | 3:08AM2.39m | 3:03PM2.30m | 3:48AM2.37m | 3:38PM2.27m | 4:26AM2.32m | 4:12PM2.21m | ||||||||
Low Tide | 6:30PM0.57m | 6:53AM0.53m | 7:20PM0.40m | 7:43AM0.54m | 8:04PM0.27m | 8:28AM0.56m | 8:45PM0.19m | 9:09AM0.59m | 9:23PM0.17m | 9:46AM0.64m | 9:59PM0.19m | 10:22AM0.71m | 10:35PM0.25m | |||||||
 |  |  | | |  | |  | | |  | | | | |  |  | | | | |
 | — | — | 6:24 | — | — | 6:22 | — | — | 6:20 | — | — | 6:18 | — | — | 6:18 | — | — | 6:16 | — | — |
 | 6:06 | — | — | 6:07 | — | — | 6:07 | — | — | 6:08 | — | — | 6:08 | — | — | 6:09 | — | — | 6:10 | — |
mm | — | — | — | — | — | 1 | — | 1 | 2 | 1 | — | — | — | — | — | — | — | — | — | — |
Temp °C | 19 | 17 | 20 | 21 | 20 | 15 | 15 | 15 | 11 | 11 | 10 | 11 | 11 | 11 | 9 | 9 | 9 | 15 | 19 | 15 |
Feels °C | 16 | 14 | 13 | 15 | 17 | 12 | 9 | 10 | 1 | 0 | -1 | 3 | 3 | 4 | 5 | 5 | 6 | 10 | 14 | 9 |
Swell 1 Height (m) Direction Period (s) | SW 15 | SW 15 | SW 14 | SW 15 | SW 15 | SW 14 | SW 13 | SW 13 | — | — | SSW 15 | SW 15 | SW 15 | SW 15 | SW 14 | SW 14 | SW 13 | SW 14 | SW 13 | SW 15 |
| kJ | 1882 | 1381 | 1006 | 927 | 606 | 357 | 257 | 130 | — | — | 75 | 3883 | 3444 | 2830 | 1830 | 1262 | 852 | 801 | 591 | 1765 |
Swell 2 Height (m) Direction Period (s) | SSW 16 | SSW 15 | SSW 15 | SSW 16 | SSW 15 | SW 20 | WSW 19 | SW 18 | — | — | — | — | — | — | — | — | SW 22 | SW 18 | SW 17 | — |
| kJ | 144 | 93 | 128 | 48 | 22 | 15 | 37 | 111 | — | — | — | — | — | — | — | — | 18 | 463 | 725 | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | S 19 | — | — | — | — | — | — | — | — | — | — | SSW 17 | SSW 17 | — |
| kJ | — | — | — | — | — | — | 7 | — | — | — | — | — | — | — | — | — | — | 168 | 229 | — |
Wind waves Height (m) Direction Period (s) | — | — | NNW 3 | N 4 | N 3 | NW 3 | SW 4 | WSW 5 | SW 13 | SW 14 | SW 14 | SW 15 | SW 15 | — | — | — | — | NW 3 | NW 3 | NW 3 |
| kJ | — | — | 9 | 13 | 4 | 1 | 9 | 64 | 2426 | 3809 | 4308 | 2648 | 2264 | — | — | — | — | 3 | 5 | 6 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 0 | 9 | 23 | 13 | 2 | 2 | 72 | 83 | 83 | 575 | 263 | 313 | 126 | 0 | 0 | 0 | 2 | 10 | 4 | 60 |
Best forecast wave conditions in Phillip Island | ||||||||||||||||||||
Best forecast wave conditions in Australia | ||||||||||||||||||||
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Information about the Cat Bay (Shelly Beach) Surf forecast
The above surf forecast table for Cat Bay (Shelly Beach) provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Cat Bay (Shelly Beach) can be found by selecting the local surf guide option on the grey menu. Our Cat Bay (Shelly Beach) surf forecast is unique since it includes wave energy (power) that defines the real feel of the surf rather than just the height or the period. If you surf the same spot (Cat Bay (Shelly Beach)) regularly then make a mental note of the wave energy from the surf forecast table each time you go. Very soon you may start to choose your surf days based on the wave energy alone combined with our forecast of favourable offshore wind conditions. Our star ratings will help here and of course you will also find the usual wave height and period predictions on our surf forecasts as well as a full break down of the swell components under our advanced users option (to reveal that, click the little Einstein character under the tide times).
Further information to help with frequently asked questions about our surf forecast for Cat Bay (Shelly Beach) may be found under the help tab on the top menu and also by moving your mouse over the question marks on the surf forecast table itself. Please always bear in mind that the forecast is for near-shore open water and local factors at each surf break influence the actual breaking wave height, such as the beach / reef profile, water depths offshore and shelter.
Cat Bay is 34 km (21 miles) from Mornington. If you plan a holiday in Phillip Island, look for hotels and other accommodation in Mornington. Mornington has rooms for a wide range of budgets as well as car hire and transport links.
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