No shortage of swell, just gotta pick the windows

Ben Matson picture
Ben Matson (thermalben)

South Australian Surf Forecast by Ben Matson (issued Wednesday 5th May)

Features of the Forecast (tl;dr)

  • Residual surf Thurs AM, new groundswell kicking in late Thurs/Fri
  • Another strong swell for Sun
  • Generally good winds on both coasts for the next four days, except Sat at Victor
  • Poor surf with gusty onshores likely early next week
  • Plenty of strong surf long term


The Mid Coast has delivered inconsistent, pulsey small waves over the last two days, around 2ft on Tuesday and 1-2ft today (see image below from U-Turns this afternoon). Victor was large (5-6ft+) but horribly blown out on Tuesday but cleaned up this morning with a brief window of light N’ly winds, which then swing back onshore mid-late morning. Size is down to 3-5ft at Middleton, and is continuing to slowly abate.

Solo traveller at U-Turns this afternoon

This week (May 6 - 7)

*Today’s Forecaster Notes will be brief as Craig is away*

We’ve got favourable conditions on tap for both coasts for the rest of the week, best suited to Victor with light to moderate northerlies, but there shouldn’t be too much strength in the gulf so the Mid should do reasonably well too (though, there is an outside risk for periods of moderate cross-shore breezes). 

As for surf, Thursday should provide similar sized waves as to what we’re seeing this afternoon - around 3-4ft across the Middleton to Day Street stretch, and a slow, inconsistent 1-1.5ft on the Mid Coast, sourced from trailing pulses of supplementary energy following Tuesday’s swell event. 

During the day, the Cape du Couedic wave buoy should register the arrival of a more pronounced increase in peak swell periods (to 16-17 seconds), which should lift surf size across both coasts late afternoon, holding into Friday morning before slowly easing. This will have originated from a stronger embedded fetch within the main storm track across the Southern Indian Ocean over the last few days. 

The bigger sets waves (from this source) will be quite inconsistent, but should push somewhere between 2ft and maybe 2-3ft on the Mid Coast - expect this very late in the day on Thursday. Yes, there’s a chance it may not show until after dark - getting the timing spot on is difficult, and the limited daylight this time of the year further reduces the window of opportunity. Friday morning is probably a safer bet, ahead of a slow easing trend through the day. But, keep an eye on the buoy and the cams and you should do OK.

At Victor, we should see the Middleton stretch back into the 3-5ft range on the bigger bombs, and it’ll be clean with light offshore winds. Well worth a surf. 

This weekend (May 8 - 9)

The models have slightly pulled back core wind strengths within the fetch generating the new swell due on Sunday. However, the storm track still looks really good (see below) so we’re on target for another nice round of strong autumn surf. 

Saturday will see a continuation of slow easing wave heights from Friday, but conditions should be OK with light winds. A weak front will clip the state during the morning, swinging overnight NW winds to the SW close to dawn, but it won’t be terribly strong. If you can only surf on Saturday (and not Sunday) leave your Victor session until after lunch, as the wind should throttle back to become light into the afternoon. 

On the Mid Coast, we’ll be back to a residual 1-2ft across the reefs on Saturday, with light variable tending onshore winds and small options for keen surfers. 

Sunday’s new swell should lift surf size to 2-3ft across the Mid Coast, and 4-5ft+ across the Middleton to Day Street stretch, with bigger options at exposed spots. Even better, winds will become light and variable through the morning as a front stands up from the west, which will eventually freshen NW winds through the afternoon - though probably not enough to greatly spoil conditions on the Mid Coast.

So, it’s shaping up to be a pretty decent weekend of waves. 

Next week (May 10 onwards)

Sunday’s approaching front has a tricky swell source attached to it, which has low confidence for surf prospects right now. It’s a deepening cut-off low that will undergo cyclogensis south of WA, and eventually track northwards up into South Australia, with strong to gale force southerly winds on its western flank.

Although it’s still early days, and the models may move around between now and the weekend, I’m most interested in the potential for a strong W/NW fetch that’ll probably develop on the low’s northern flank - this could be a good source for the Mid Coast. However, there’s a fair chance that any decent swell produced by this low will be accompanied by poor conditions under strong onshore winds from either the west or the south.

Of course, a slight change in the position of the cut-off low could swing the pendulum back the other way. So right now, don’t go planning anything (surf, or non-surf). 

Regardless, the Southern Ocean is very active at the moment, and of what happens early next week, chances are very high than the second half of next week and the weekend will see an immediate return to strong autumn/winter synoptics and plenty of strong swells for the SA coast.

More on this in Friday’s update. 


thermalben's picture
thermalben's picture
thermalben Thursday, 6 May 2021 at 2:19pm

CdC buoy has a faint signal at 18-19 seconds (see square on left). It's not showing on Tp trace as there's a stronger leftover S/SE swell at ~13 seconds in the water (square on right), however this could be the forerunners of the new event expected very late today and into tomorrow.

SA Wetdog's picture
SA Wetdog's picture
SA Wetdog Friday, 7 May 2021 at 8:19am

Wtf whoever did the report this morning. 3-4 foot off Middleton you are kidding me!

thermalben's picture
thermalben's picture
thermalben Friday, 7 May 2021 at 10:42am

Head high in the Bay (coloured rashies... is a comp on?), looks a little bigger off the point and up towards Day Street.

Kellya's picture
Kellya's picture
Kellya Friday, 7 May 2021 at 11:21am

Carnage on the Knights cam!