South Australian Surf Forecast by Ben Matson (issued Wednesday July 17th)

Features of the Forecast (tl;dr)

Mid Coast

• Small waves building Thurs PM
• Possible NW stormy Fri, W/SW stormy Sat, easing Sun but remaining bumpy
• Very good surf expected Mon with a solid groundswell and light winds
• Plenty of surf for the rest of the week

South Coast

• Average surf Thurs, small and clean Fri
• Windy and building Sat, becoming solid Sun with offshore winds
• Large clean surf Mon, easing a little from Tues onwards with generally good winds

Recap

The Mid’s been tiny and Victor’s been suffering from strong onshore winds. There’s been no shortage of size down south though, building to 4-6ft yesterday and easing to 3-5ft throughout the day today.

This week (Jul 18 - 19)

No major changes to the outlook for the rest of the week.

The current southerly airstream will abate overnight to become light by Thursday morning, before winds swing light to moderate NW throughout the afternoon. 

Surf size will be easing at Victor but I’m doubtful that we’ll see properly clean conditions until Friday when we’ll see strengthening N/NW winds iron out all of the lump and bump. 

As for wave heights, Thursday will see a mix of easing short range southerly swell and building long range SW groundswell that should manage 2-3ft sets at Middleton (the latter not really showing until the afternoon). It’ll be worth a surf but there will be some leftover wobble at times, especially in the morning.

Friday will see this swell source ease - consider yourself lucky if you find any leftover decent sets across the Middleton stretch as it’ll be down to 2ft or less, so exposed beaches will be your best bet for a wave. 

Along the Mid Coast, Thursday’s new groundswell won’t amount to much but there should be some small arvo waves in the 1-2ft range, slow but workable if you’ve got the right kind of board.

Friday will see this small groundswell source throttle back, as the N/NW tending NW breeze strengthens, concurrently building some local windswell across the coast. It’s rare that we see anything rideable from these kinds of patterns, but this scenario is shaping up to display enough strength in the wind - with just enough west in the direction - to throw up a few choppy waves in the 2-3ft range by the afternoon (bigger south of the Mid), maybe even something along the metro beaches if you’re desperate. 

This weekend (Jul 20 - 21)

The models have strengthened things in the last few runs so there’s been a subsequent upgrade in surf and wind for the forecast period.

Strong W/SW winds will push across the coast overnight Friday, generating a decent stormy on the Mid for Saturday (3-5ft). There’ll be plenty of underlying groundswell in the mix too so we should see options right along the coast including metro beaches. 

Winds will ease back into Sunday and veer NW, but remain strong enough to spoil surface conditions. Expect a mix of swells to maintain 3-4ft sets across the Mid with small waves at metro beaches if you’re desperate.

Down south, Saturday’s strong to gale force W/SW winds will probably write-off conditions for the day. The strong westerly component in the swell direction will keep a lid on surf size but 3-4ft sets at Middleton are expected throughout the day (bigger at exposed spots, but hardly anywhere out of the wind).

Sunday’s shaping up much better as winds veer back to the NW, and surf size builds a little more as a secondary SW groundswell starts to make its presence felt, showing 4-5ft at Middleton with bigger waves at the regional swell magnets. 

Let’s fine tune this outlook in more detail on Friday.

Next week (Jul 22 onwards)

So, the storm track for the end of this week and weekend looks very impressive on the synoptic charts, but once you analyse the surface wind field, it starts to fall apart at the seams, just a little bit (see below). 

Whilst the greater swell window will be active under some kind of reasonably-aligned fetch, wind strengths won’t be continuous across the basin - with patchy regions of gales intermixed with regions of differently aligned fetches, of lesser strength.

Is this a bad thing? Not necessarily for the Mid and South Coasts (any clean surf is good surf, hey?), but worth considering if you’re travelling further afield, because the most likely outcome will be an ocean with multiple swell trains from a broad directional spread (W thru' SW) displaying different sizes and periods. This overall concept is actually quite beneficial for beachbreaks in NSW and Qld, but it’s not great for Southern Ocean reefs and points, which are designed to respond best to singular long period swell events. Anyway, it’s a point I thought was worth mentioning because of the way the synoptic charts are evolving.

So now that I have sufficiently lowered your expectations, allow me to boost it back up again, with a favourable wind forecast for Monday, as a weak right of high pressure allows winds to become light NW into Monday morning, at the same time swell energy reaches a peak across both coasts.

We should see solid 4ft sets across the Mid Coast - this is pushing towards the upper end of the potential size range we see from groundswells - and 4-6ft surf across the Middleton stretch (bigger 8ft sets at the bombies). 

A slight easing of swell is then expected into Tuesday, though still maintaining 2-3ft+ surf on the Mid, and 4-5ft surf at Middleton, however winds will freshen from the NW which will only favour the South Coast.

Wave heights should then ebb and flow in the 3-4ft range at Middleton for the rest of the week, with rideablw waves every day along the Mid - though bumpy with onshore winds at times (there will be favourable windows, but it’s too early to identify them right now).

Long term has a whole stack of swell on the way as the storm track resumes normal winter programming. So, there’s plenty to look forward too.

See you Friday.