South Australian Surf Forecast by Ben Matson (issued Monday 25th March)

Best Days: Tues: large early peak at Victor (small but still decent on the Mid), easing and improving as onshore winds rapidly ease and become variable. Wed/Thurs: easing swells becoming small everywhere but clean with light winds. Fri: moderate+ new swell building across both coasts, holding Sat, easing Sun, with freshening W/SW winds, temporarily easing W/NW Sat then returning to the W/SW Sun. Mon/Tues: very large surf redeveloping down south.

Recap: Easing swells over the weekend didn’t offer a lot across the Mid, just occasional 1ft sets both days, whilst conditions were lumpy tending bumpy on Saturday with early W’ly winds swinging SW then S’ly, ahead of freshening NW tending W/NW winds on Sunday. Today’s seen strengthening winds and building swells that reached an impressive height this afternoon, somewhere around 8ft across the South Coast’s exposed breaks, whilst the Mid Coast built to a 3-5ft stormy under gusty onshore winds (with a few small waves on the metro beaches too).

This week (Mar 26 - 29)

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The Cape du Couedic wave buoy recorded some impressive wave heights today, up in the size range we see perhaps a couple of times per year (Hsig 7.5m, Hmax 13m). 

This event will slowly ease from Tuesday though we’ll still see large surf through the morning, as there was a secondary intensification of the low late this afternoon SW of Tasmania that generated a spike in wave heights at the Cape Sorell buoy a few hours ago (Hsig 8.2m, with Hmax an incredible 16.5m). This should keep the South Coast elevated with 6ft to maybe 8ft surf early morning, easing to 4-5ft by lunchtime. 

This secondary swell was generated inside the Mid Coast’s swell shadow (thanks to Kangaroo Island) so we’ll see easing residual swells here, with decent 2-3ft sets for much of the day. 

Conditions across both coasts should improve quickly with winds becoming light and variable. Expect a few wobbles in the morning, particularly down south.

The trend for the rest of the week is steadily down, with variable winds Wednesday and Thursday tending SW into Friday and freshening as a series of cold fronts clip the southern part of the state. They’ll also generate a building round of new SW swells thanks to respectable activity through the swell window all week - not terribly strong, but persistent and pushing to within a reasonable distance of the South Australian swell window. 

The swell direction won’t be great for the Mid Coast but the storm track is conducive for an active sea state, so we should see 2ft+ waves here into the afternoon (smaller earlier). Expect Middleton to build from a reasonable 2-3ft early up to 3-5ft by late afternoon. The afternoon onshores will become fresh but not overly strong, so there’ll be workable options. 

This weekend (Mar 30 - 31)

Friday’s late increase in swell is expected to hold into Saturday before easing a little through Sunday. 

Although we may possibly see trailing SW winds early Saturday, winds will ease throughout the day and swing lighter W’ly, before veering light W/NW late in the day and holding here into Sunday morning, ahead of a fresh W’ly change as a stronger front slide to the south. 

Winds won’t be quite as strong across the Mid Coast and we should see fun surf both days around 2ft+, perhaps a little smaller on Sunday before the wind picks up into the afternoon and adds some windswell into the mix.

Down south, size will ease slowly from 3-5ft to 3ft at Middleton from Saturday morning into Sunday morning, ahead of a possible late kick in new groundswell Sunday afternoon. 

Overall, plenty of surf but patchy conditions for the weekend. Still worth your attention though.

Next week (April 1st onwards)

We’ve got some really large waves due for the South Coast early next week. 

And in contrast to the current swell event - sourced from a powerful low, positioned relatively close to the coast - next week’s waves will be sourced from a polar low developing SE from Heard Island (off the Ice Shelf) later Thursday and Friday, before it tracks NE towards the SA/Vic region over the weekend. These are one of my favourite weather systems for SA/Vicco swells, as the slightly more S’ly (of SW) swell direction provide a little more size across the South Coast stretch compared to SW or W/SW swells. And the bulk swell production happens much further from the mainland so the groundswell quality is better. Lastly, the fronts usually clear quickly the east too so we often see the peak of the swell coincide with light winds. 

If model guidance holds true - and we’ve still got a few days to go before confidence starts to increase - we could be looking at a peak somewhere near 8ft+ across exposed South Coast breaks. I’m not keen on the swell direction for the Mid Coast but we should see small clean waves here regardless. 

More on this in Wednesday’s update.