Active Indian Ocean continues to generate plenty of swell with a few windows of clean conditions this week

Steve Shearer picture
Steve Shearer (freeride76)

Western Australian Surf Forecast by Steve Shearer (issued Mon September 18th)

Features of the Forecast (tl;dr)

  • More large surf and onshore winds Tues
  • Shift to more S’ly winds from Wed, tending E’ly Thurs/Fri plenty of surf
  • Super long period W/SW swell Thurs/peaking Fri
  • Swell building Sat with onshore winds, peaking Sun with a window of offshore winds
  • Offshore winds possible Mon AM with solid surf
  • More solid surf in the medium term with brief windows of clean conditions in a general onshore flow


Lots of size and onshore winds over the weekend with 8-10ft surf between the Capes Sat, 3-4ft in Perth with a window of cleaner conditions under light S’ly winds (E/NE in Perth). Onshore winds freshened again Sun with 4-6ft surf in the SW corner, with bigger 6-8ft sets in the a’noon. Today has eased in size with onshore winds and 3-5ft surf in the Margarets region and 2-3ft surf in Perth/Mandurah. 

Another day with size and onshore winds

This week and next week (Sep 18 - 29)

No major change to the outlook. High pressure at sub-tropical latitudes is maintaining a ridge of W’ly airflow with the southern storm track over the SW corner. A cold front tips the state tomorrow enhancing the W’ly flow. An approaching high looks to suppress the storm track leading to brief period of smaller surf across the SW with some windows of cleaner conditions likely. 

Solid rebuild in SW swell pushes surf back to up to 6-8ft+ between the Capes but with strong onshores it’ll be protected spots only and onshore beachies to 3ft in Perth/Mandurah.

Windows of cleaner conditions then look likely Wed AM, with a lighter S’ly flow, tending more E-SE in Perth and Thurs where light E’ly offshore winds look to offer the first proper clean clean day for weeks.

Plenty of solid SW swell Wed to 6ft+ with 8ft sets, easing back Thurs to 4-6ft in Margarets, 2-3ft in Perth/Mandurah.

Keep an eye out for super long period W/SW swell from an African storm we mentioned last week. These swell periods will be in excess of 20 seconds, through Thurs into Fri. Not the main swell source but still supplying some long range energy into the mix. 

Fri morning sees this swell source peak with 5-6ft sets and light SE winds favouring Margaret river reefs. Plenty of SW energy fills the holes in between with similar sized sets. 

Into the weekend and a broad, gale force fetch tracking NE of Heard Island Wed/Thurs (see below) delivers another payload of solid SW swell expected to build in on Sat into the 4-6ft range after an undersized start.

Winds look better for Sun and with plenty of swell from a long trailing fetch we’ll see sets to 6ft+ under light S’lies which will open up some of the more sheltered bays in the SW. Winds should be more SE-E in Perth/Mandurah through the morning.

Looks like a brief window of NE winds Mon under solid surf to 6ft+ before another series of W’ly wind episodes rise up and tip the SW of the state. 

The Indian Ocean storm track remains active with mid-size disturbances separated by a day churning through the central/South-eastern part of the Basin early next week.

We’ll see how it looks on Wed but we’ll be looking at more solid 6ft+ surf next week with brief periods of cleaner conditions in amongst a general W’ly flow.

Seeya Wed.


smokeydogg's picture
smokeydogg's picture
smokeydogg Monday, 18 Sep 2023 at 8:25pm

Nice work with the forecasts, just wondering if you will keep updating the Indo forcast for Sept ?