South Australian Forecast by Ben Matson (issued Friday 14th October)

Best Days: Sat: small clean surf down south. Sun: chance for a small reasonable wave on the Mid in the a'noon. Mon: small waves on the Mid, though possibly bumpy. Tues: chance for a very late pulse in new groundswell (more likely Wed). Wed: strong, large surf down south and good waves on the Mid with great conditions. 

Recap: Small residual swells padded out the Mid Coast on Thursday whilst a decent groundswell maintained fun waves across the South Coast. Tiny conditions have persisted on the Mid today with smaller, easing swells down south. 

This weekend (Oct 15 - 16)

Saturday is your best chance for a wave this weekend down south, whilst there is some potential for the Mid Coast on Sunday afternoon.

A cold front will approach the WA coast today, pushing into the Bight on Saturday and this will strengthen northerly winds about the Fleurieu Peninsula during the day. With no new swells expected across the region we can expect tiny, choppy surf across the Mid Coast and small clean waves at Victor best suited to exposed spots like Waits, Parsons and Goolwa. 

It won’t be very big - only 2ft or so - but there’ll be a few slow inconsistent sets if you’re keen.

The front in the Bight is expected to weaken and track inland at a point probably west of Adelaide throughout Sunday. Model guidance is suggesting we’ll see a local W/NW tending W/SW change throughout the day but I don’t think there’ll be a lot of strength in it, however with this risk of a more cross-shore (possibly cross-onshore) flow down south, I think Saturday is the pick of the two days. In any case there’s no new swell of any significant expected - we’ll see a small distant W/SW groundswell maintain rideable energy across exposed beaches but this direction won’t be favourable for any notable size. 

The Mid Coast has a few interesting possibilities on Sunday though. As the front enters the western Bight on Saturday morning it’s develop a fetch of low-end westerly gales, aimed within the Mid’s swell window. This fetch will move around within the Bight as the front tracks east, and it should be enough to kick up a small swell throughout Sunday, probably somewhere in the 2ft range (more likely in the afternoon than the morning). 

Obviously, this will only be of any value if local winds play ball, and it looks like the morning will see freshening W/NW winds. However as the front slides NE across the West Coast during the day, we may see the onshore flow ease into the afternoon, improving conditions across the gulf. 

At this stage confidence isn’t very high for any notable waves, but it’ll be worth keeping an eye on the local obs and the South Port surfcam throughout the day as I have a sneaking suspicion that we could see a fun window of opportunity through Sunday afternoon. 

Next week onwards (Oct 17 onwards)

Approaching fronts in the Southern Ocean will freshen winds from the W/NW on Monday, and whatever small W’ly swell we see on the Mid on Sunday afternoon should persist into Monday morning though probably weaken a little during the day. So right now there’s a chance for occasional bumpy 2ft sets throughout the day. 

This small W’ly swell won’t be favourable for the Victor coast so expect small clean waves at protected western ends, and that’s about it. There won’t be much size across the Middleton stretch.

Of much more interest is an intense polar low - currently forming SE of Madagascar - that's expected to strengthen considerably over the weekend as it tracks past Heard Island, enroute through the Southern Ocean beneath Australia.

By Monday this system is expected to encompass much of the Southern Ocean waters beneath the continent, and whilst core winds will have weakened from Saturday’s peak (40-50kts), the broadening width of the fetch and its ideal alignment within our swell window means we’ve got an excellent groundswell due to arrive mid-week.

Tuesday looks like it’ll mainly see continuing small conditions across both coasts with freshening W'ly winds (maybe W/NW early) tending W/SW during the day as the front clips the coast. Current model guidance has the leading edge of this new groundswell approaching the SA coast late afternoon, so theoretically there is an outside chance for a late pulse of new groundswell - but current indications are it’ll probably occur too late to benefit surfers (I’ll update over the weekend though as the models firm things up). Certainly worth pencilling in the diary though.

As such, Wednesday is shaping up to see the bulk of the new swell fill in. Tuesday’s front will have cleared to the east overnight with another front expected to push up south of SA, and this should steer the winds back around to a light NW flow. In fact, winds should be variable across the Mid Coast early morning.

And, size? I’m really impressed with the way the models are tracking this system through the Southern Ocean - it reaches maturity in an ideal part of the swell window (south of WA) but also has most of its initial stages at a reasonably low latitude (50S or lower) which means it’ll spend a lot of time within our swell window. That ramps up the size and strength potential for the South Coast but we should also see some nice lines of groundswell push through the gulf too.

At this stage we should see solid 6-8ft surf across exposed parts of the South Coast on Wednesday, whilst he Mid Coast is looking at tidally influenced 2-3ft surf throughout the day (smaller on the outgoing phase). Winds will pick up from the NW during the afternoon but at this early stage I’m reasonably confident that the Mid Coast will remain pretty clean all day. 

Wednesday’s peak in swell will ease rapidly into Thursday with pre-frontal northerly winds swinging W’ly as another change crosses the region. Strong SW winds trailing this next fronts (earlier in its cycle, around Monday SW of WA) will renew moderate swell for the region into the afternoon and throughout Friday, possibly back up into the 4-5ft range across the South Coast and with 2-3ft surf across the Mid Coast, though with accompanying W’ly (Thurs PM) tending SW (Friday) winds. 

So there’s lots to get excited about - well worth moving your diary around for Wednesday.