Surf Forecasts:
Big Rock surf forecast from 21 Aug 2026:
- Best quality surf: Wednesday 26 Aug, 8AM (local time) - 16ft (5.0m), 19s period, WSW swell with cross-onshore winds.
- Most powerful swell: Wednesday 26 Aug, 8AM (local time) - 16ft (5.0m), 19s period, WSW swell with 19,635 kJ wave energy.
- Next surfable swell (1★+): Friday 21 Aug, 8PM (local time) - 10ft (3.0m), 14s period with SW swell.
Best Forecast Surf Conditions for Big Rock this week:
The surf forecast for Big Rock over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Aug 21) at 8PM. The primary swell is predicted to be 3.0m and 14s period with a secondary swell of 1.4m and 19s. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Big Rock in the next 16 days are 5.0m 19s and forecast to arrive on Wednesday (Aug 26) at 8AM. Winds are predicted to be cross-onshore at the time the swell arrives.
| Wave Type | Time (AWST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 8PM (Fri 21st Aug) | 10ft (3.0m) 14s |
| Best Surf | 8AM (Wed 26th Aug) | 16ft (5.0m) 19s |
| Most Powerful | 8AM (Wed 26th Aug) | 16ft (5.0m) 19s |
Table - best surf conditions forecast for Big Rock over the next 16 days.
The Lowdown
G’day, Rusty here. Let’s get into the outlook for Big Rock.
It’s gonna be a test of patience for the first week and a half, with the wind messing up more than a few sessions. The water’s running about 66°F, which is a touch warmer than typical for this time of year.
Friday the 21st kicks things off with a solid 12ft SW groundswell at 14 seconds, but that 15 km/h SSW cross-breeze is going to make things bumpy. The energy is strong at 6377, but it’s not going to be clean. You’ll get some, but you’ll have to work for it.
Saturday the 22nd is a step back. The swell is still there, 10ft in the morning and dropping to 8ft in the afternoon, but the wind picks up to a moderate 25 km/h and it’s messy.
Sunday the 23rd has a cross-onshore wind, and it’s choppy. Not great.
Monday and Tuesday, the 24th and 25th, the wind is cross-onshore again, and the surf stays in the 8ft to 10ft range. Tuesday afternoon brings rain and a fresh breeze and just looks poor.
Now, Wednesday the 26th. The swell explodes to a massive 18ft from the WSW, with a very long 18-second period. The energy is huge at 18328. But this is way too big for this reef. It’ll be a close-out and dangerous. A total pass.
The rest of that week stays in the 12ft range with that moderate cross-shore wind, keeping things choppy.
Finally, a window opens. Friday morning, the 28th of August. The wind drops to a light 5 km/h cross-off, and the swell settles to a clean 8ft from the SW with a 12-second period. This will be the first clean session since the start, and it’s a good one.
Saturday the 29th starts clean with a small 4ft SW groundswell with a long 17-second period in the morning, but the afternoon gets bumpy again as the swell builds to 8ft.
The following week looks better. Monday the 31st has a cross-off breeze in the afternoon with a 10ft WSW swell, and the energy is building. A solid session. Tuesday the 1st of September is another standout, with a clean 8ft swell and light winds in the morning.
The real gem is Friday morning, the 4th of September. We’ve got an 12ft SW swell with a 16-second period and glassy conditions. The energy is strong at 6072. This is the day for a proper reef wave.
But the biggest one is Saturday morning, the 5th. A massive 16ft of WSW swell with a 16-second period and light offshore winds. The energy is enormous at 12448. It’s big, it’s powerful, and it’s only for experts. This is the standout of the entire run, but it’s a week out, so treat it with some caution.
So, be patient. The first few days are a write-off, but look at the 28th, the 1st, and especially the 4th and 5th of September. The 5th is the one to circle. Get after it.
Rusty.
Short Range ForecastSome drizzle, heaviest during Sun morning. Very mild (max 16°C on Fri afternoon, min 12°C on Fri night). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 23mm), heaviest during Tue night. Very mild (max 17°C on Tue morning, min 13°C on Tue night). Mainly strong winds. | |||||||||||||||||||
Fri 21 | Saturday 22 | Sunday 23 | Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | ||||||||||||||
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 14 | WSW 18 | SW 16 | SW 16 | SW 14 | SW 13 | SW 13 | WSW 15 | WSW 14 | WSW 13 | WSW 12 | WSW 14 | WSW 14 | WSW 15 | WSW 18 | WSW 17 | WSW 16 | WSW 14 | WSW 14 | WSW 13 |
Wave Graph  | ||||||||||||||||||||
 kJ | 5116 | 2603 | 3953 | 3137 | 1785 | 2207 | 1975 | 4485 | 2862 | 2021 | 1667 | 3801 | 3406 | 5622 | 18328 | 15082 | 8912 | 5450 | 4381 | 2537 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-off | cross | cross | cross | cross-on | cross | glassy | cross-on | cross-on | cross-on | cross | cross | cross-on | cross-on | cross-on | cross-on | cross | cross | cross-off |
High Tide | 3:39AM0.84m | 5:28AM0.87m | 6:35AM0.90m | 7:24AM0.91m | 8:07AM0.91m | 8:49AM0.90m | 11:28PM0.59m | |||||||||||||
Low Tide | 3:41PM0.29m | 3:54PM0.28m | 4:05PM0.29m | 4:17PM0.29m | 4:29PM0.31m | 4:41PM0.32m | 4:53PM0.34m | 2:29AM0.56m | ||||||||||||
 |  |  |  |  |  | | | | | | |  |  | | | | | | | |
 | — | — | 6:52 | — | — | 6:50 | — | — | 6:48 | — | — | 6:48 | — | — | 6:47 | — | — | 6:46 | — | — |
 | 5:53 | — | — | 5:53 | — | — | 5:54 | — | — | 5:55 | — | — | 5:55 | — | — | 5:57 | — | — | 5:58 | — |
mm | — | — | — | — | — | 1 | — | — | — | — | — | — | 1 | 14 | 3 | 3 | 2 | — | — | — |
Temp °C | 16 | 15 | 15 | 15 | 15 | 14 | 13 | 13 | 14 | 15 | 16 | 17 | 17 | 17 | 14 | 14 | 14 | 14 | 14 | 14 |
Feels °C | 14 | 12 | 11 | 9 | 12 | 10 | 8 | 10 | 11 | 10 | 11 | 11 | 11 | 10 | 8 | 8 | 7 | 8 | 8 | 9 |
Swell 1 Height (m) Direction Period (s) | SW 14 | SW 14 | SW 16 | SW 16 | SW 14 | SW 13 | SW 13 | WSW 15 | WSW 14 | WSW 13 | WSW 12 | WSW 14 | WSW 14 | WSW 15 | WSW 18 | WSW 17 | WSW 16 | WSW 14 | WSW 14 | WSW 13 |
| kJ | 5116 | 2603 | 3953 | 3137 | 1785 | 2207 | 1975 | 4485 | 2862 | 2021 | 1667 | 3801 | 3406 | 5622 | 18328 | 15082 | 8912 | 5450 | 4381 | 2537 |
Swell 2 Height (m) Direction Period (s) | SW 20 | WSW 18 | — | — | WSW 20 | WSW 18 | WSW 16 | — | — | — | WSW 17 | — | — | NW 7 | — | — | — | — | — | — |
| kJ | 1261 | 2490 | — | — | 75 | 360 | 1194 | — | — | — | 601 | — | — | 219 | — | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | WSW 22 | — | — | — | — | — | — |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | 879 | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | — | SSW 5 | — | — | — | — | — | — | — | NW 5 | NW 6 | — | — | — | — | — | — | — |
| kJ | — | — | — | 45 | — | — | — | — | — | — | — | 102 | 216 | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 1 | 0 | 34 | 359 | 20 | 2 | 20 | 0 | 27 | 302 | 53 | 221 | 202 | 459 | 251 | 251 | 2 | 34 | 20 | 0 |
Best forecast wave conditions in Margaret River | ||||||||||||||||||||
Best forecast wave conditions in Australia | ||||||||||||||||||||
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Information about the Big Rock Surf forecast
The above surf forecast table for Big Rock provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Big Rock can be found by selecting the local surf guide option on the grey menu. Our Big Rock 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 (Big Rock) 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 Big Rock 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.
Big Rock is 85 km (53 miles) from the city of Bunbury. If you plan a holiday in Margaret River, look for hotels and other accommodation in Bunbury. Bunbury has rooms for a wide range of budgets as well as car hire and transport links.
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