Surf Forecasts:
Secret Harbour surf forecast from 17 Aug 2026:
- Best quality surf: Wednesday 19 Aug, 11PM (local time) - 10ft (3.0m), 16s period, WSW swell with glassy winds.
- Most powerful swell: Tuesday 18 Aug, 2AM (local time) - 13ft (4.0m), 15s period, W swell with 7,074 kJ wave energy.
- Next surfable swell (1★+): Wednesday 19 Aug, 11PM (local time) - 10ft (3.0m), 16s period with WSW swell.
Best Forecast Surf Conditions for Secret Harbour this week:
The surf forecast for Secret Harbour over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Wednesday (Aug 19) at 11PM. The primary swell is predicted to be 3.0m and 16s period. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Secret Harbour in the next 16 days are 4.0m 15s and forecast to arrive on Tuesday (Aug 18) at 2AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.5m 3s period and expected on Saturday (Aug 22) at 5PM.
| Wave Type | Time (AWST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 11PM (Wed 19th Aug) | 10ft (3.0m) 16s |
| Best Surf | 11PM (Wed 19th Aug) | 10ft (3.0m) 16s |
| Most Powerful | 2AM (Tue 18th Aug) | 13ft (4.0m) 15s |
Table - best surf conditions forecast for Secret Harbour over the next 16 days.
The Lowdown
G’day, Rusty here. We’ve got a solid run of swell on the way for Secret Harbour, but it’s not all smooth sailing—you’ll need to pick your windows carefully. The forecast kicks off Monday afternoon with a big, raw south-west swell, but it’s a write-off with strong onshore wind. From Tuesday, the energy drops a notch but the quality improves, and there are some absolute gems tucked in the middle of the outlook if you can wait.
Let’s start with the action. Tuesday morning the 18th of August sees a 12 ft west swell rolling in with a very long 16-second period and light west wind. That’s heavy, groundswell energy—moderate to strong combined energy (6388) pushing through. The morning session is marginal on the tide, but the power is there. By Wednesday morning the 19th, things clean right up: a 8 ft west-south-west swell, 15-second period, and light north cross-offshore breeze. That’s clean, lined-up, and excellent for experienced surfers. The combined energy is strong (2687) and the water’s sitting at a comfortable 64°, which is about average for this time of year.
Thursday morning the 20th offers another clean 8 ft west-south-west swell, 16-second period, with near-glass cross-shore wind. The energy remains strong (3594) and the conditions are tidy. But the real standout this week comes Friday morning the 21st of August: 7 ft west-south-west swell, 15-second period, and flat glassy conditions with a light south-east breeze—that’s as clean as it gets. Combined energy is strong (2048) and the wave quality is excellent for experienced surfers. If you can be out there, this is the session. Saturday afternoon the 22nd also delivers glassy 6 ft west-south-west swell with 16-second period and light north-north-east breeze—another clean, sweet window.
Sunday the 23rd turns ugly with fresh cross-onshore winds and poor surf, so give that a miss. Monday the 24th morning bounces back with a clean 7 ft west swell, 14-second period, and light north cross-offshore breeze—another good one for the experienced crew. Tuesday the 25th morning brings a bigger 10 ft west-south-west swell, 14-second period, but it’s cross-shore and a bit lumpy. That’s more of a power session for experts. Wednesday the 26th morning returns to glassy conditions with a 7 ft west-south-west swell, 16-second period—beautiful.
Looking further out, Thursday the 27th morning is another clean gem: 5 ft west-south-west swell, 14-second period, glassy and cross-offshore. Friday the 28th afternoon offers glassy 7 ft west-south-west swell with 15-second period and clean cross-offshore wind—another top pick. Saturday the 29th afternoon gives us a nice offshore 5 ft west-south-west swell, 14-second period, gentle offshore wind and clean. Sunday the 30th has a big 8 ft west swell with 19-second period—very long-period groundswell—but cross-shore winds make it tricky; better for points and reefs than a sandbar.
Monday the 31st of August and Tuesday the 1st of September are ruined by strong to near-gale onshore winds and messy, poor surf, so steer well clear.
Overall, the best windows are Friday the 21st of August morning, Saturday the 22nd of August afternoon, and Wednesday the 26th of August morning. That Friday glassy session is the true standout. Secret Harbour is a consistent, exposed sandbar that handles west-south-west swell well, and with these long-period swells the sets will have real push. It’s an advanced wave, and crowds are sometimes expected—so be ready to share. Enjoy.
Rusty
Short Range ForecastLight rain (total 2mm), mostly falling on Mon night. Very mild (max 17°C on Wed morning, min 13°C on Wed night). Winds decreasing (strong winds from the WSW on Mon night, calm by Thu morning). | Days 5-7 Weather SummaryLight rain (total 6mm), mostly falling on Sun morning. Warm (max 23°C on Sat afternoon, min 13°C on Thu night). Winds increasing (calm on Fri morning, fresh winds from the SW by Sun afternoon). | ||||||||||||||||||
Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | ||||||||||||||
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) | W 15 | W 16 | W 16 | W 16 | W 15 | WSW 16 | WSW 16 | WSW 16 | WSW 16 | WSW 16 | WSW 15 | WSW 14 | WSW 14 | WSW 17 | WSW 16 | WSW 14 | WSW 14 | WSW 16 | WSW 14 |
Wave Graph  | |||||||||||||||||||
 kJ | 7074 | 6388 | 5848 | 3784 | 2906 | 4193 | 4467 | 3594 | 2958 | 2511 | 1994 | 1667 | 1285 | 2040 | 1498 | 911 | 752 | 1150 | 1393 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-off | glassy | cross-on | cross-off | glassy | cross-on | cross-off | cross-off | cross-off | on | on | cross-on | cross-on |
High Tide | 00:27AM0.76m | 00:58AM0.78m | 1:41AM0.79m | 2:37AM0.79m | 3:48AM0.80m | 5:09AM0.82m | |||||||||||||
Low Tide | 4:26PM0.43m | 4:21PM0.38m | 4:21PM0.34m | 4:16PM0.32m | 4:03PM0.31m | 3:50PM0.31m | |||||||||||||
 |  | |  |  | | | | |  | | | | |  | |  | | | |
 | — | 6:50 | — | — | 6:50 | — | — | 6:48 | — | — | 6:48 | — | — | 6:47 | — | — | 6:46 | — | — |
 | 5:50 | — | 5:50 | — | — | 5:51 | — | — | 5:52 | — | — | 5:52 | — | — | 5:52 | — | — | 5:53 | — |
mm | 1 | — | — | — | — | — | 1 | — | — | — | — | — | — | — | — | 3 | 2 | 1 | — |
Temp °C | 16 | 15 | 16 | 16 | 17 | 17 | 17 | 15 | 16 | 15 | 15 | 17 | 17 | 21 | 23 | 20 | 17 | 16 | 16 |
Feels °C | 7 | 12 | 12 | 13 | 14 | 14 | 15 | 15 | 14 | 13 | 14 | 14 | 15 | 17 | 19 | 18 | 14 | 10 | 10 |
Swell 1 Height (m) Direction Period (s) | W 15 | W 16 | W 16 | W 16 | W 15 | WSW 16 | WSW 16 | WSW 16 | WSW 16 | WSW 16 | WSW 15 | WSW 14 | WSW 14 | WSW 17 | WSW 16 | WSW 14 | WSW 14 | WSW 16 | WSW 14 |
| kJ | 7074 | 6388 | 5848 | 3784 | 2906 | 4193 | 4467 | 3594 | 2958 | 2511 | 1994 | 1667 | 1285 | 2040 | 1498 | 911 | 752 | 1150 | 1393 |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | WSW 22 | WSW 19 | — | — | W 20 | W 18 | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | 98 | 502 | — | — | 119 | 300 | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | S 4 | — | — | NNW 3 | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | 4 | — | — | 2 | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | NNE 3 | N 3 | W 3 | SW 6 | WSW 8 | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | 4 | 6 | 4 | 176 | 306 | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 442 | 356 | 307 | 328 | 177 | 101 | 0 | 0 | 50 | 0 | 0 | 101 | 0 | 49 | 0 | 278 | 369 | 177 | 21 |
Best forecast wave conditions in Perth City Coast | |||||||||||||||||||
Best forecast wave conditions in Australia | |||||||||||||||||||
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Information about the Secret Harbour Surf forecast
The above surf forecast table for Secret Harbour provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Secret Harbour can be found by selecting the local surf guide option on the grey menu. Our Secret Harbour 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 (Secret Harbour) 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 Secret Harbour 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.
Secret Harbour is 13 km (8 miles) from Mandurah. If you plan a holiday in Perth City Coast, look for hotels and other accommodation in Mandurah. Mandurah has rooms for a wide range of budgets as well as car hire and transport links.
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