Large and average Thursday, cleaner Friday, good Sunday

Craig Brokensha picture
Craig Brokensha (Craig)

South Australian Forecast (issued Wednesday 9th July)

Best Days: Friday morning down South, later Saturday on the Mid for tiny waves, Sunday down South, Monday down South


The South Coast offered the best waves yesterday with a small swell favouring exposed beaches and strengthening offshore winds.

Today conditions were clean at dawn but an onshore change moved through shortly afterwards with a small swell, while the Mid Coast was offering a semi-stormy mix of swells to 2-3ft with strengthen onshores. We should see the swell build further into this afternoon as winds swing stronger SW with a front passing over the region.

This week (Jul 9 – Jul 11)

Today's increase in large W/SW groundswell across both coasts should peak overnight and ease through tomorrow, but the South Coast will see a large SW swell overriding the underlying W/SW swell.

This will be produced by the mid-latitude frontal system currently moving across us, with a fetch of SW gales forecast to be projected towards the South Coast this afternoon and evening, with a weaker trailing S/SW fetch into tomorrow morning.

A large stormy SW swell will result with fresh to strong but easing SW winds across the coast tomorrow, with Middleton expected to be in the 5-6ft range with larger rogue sets out at Waits. The Mid Coast should ease from 2-3ft or so and then further back to 2ft on Friday as onshore winds persist.

The South Coast will offer much better waves Friday morning as Thursday's swell continues to ease under W/NW offshores. A late afternoon SW change will bring with it poor conditions but also the start of a large S/SW groundswell due into Saturday (discussed below).

This weekend onwards (Jul 12 onwards)

The weekend's large S/SW groundswell is still on track and winds are now looking more favourable than they were on Monday.

The formation of this swell is linked to a strong but weakening amplification of the Long Wave Trough moving across south-eastern Australia later this week.

With this a vigorous polar front is being steered up towards us and Victoria under the influence of the LWT. A broad but slowly weakening fetch of SW gales has been projected up towards us from yesterday and will continue through until Friday evening.

A large S/SW groundswell will result, arriving later Friday but really filling in Saturday, reaching 5-6ft across Middleton with the odd bigger 8ft bomb at Waits into the afternoon. Unfortunately the frontal system linked with the swell pushing through Friday afternoon will leaving fresh but easing S/SW winds in its wake Saturday.

The Mid Coast should offer cleaner conditions with 1ft+ of swell and S/SW tending S/SE winds into the late afternoon.

Sunday however is looking really good as a ridge of high pressure quickly slides in from the west tending winds variable across the Fleurieu Peninsula. With local land breezes (offshores) kicking in this should see light offshore winds developing across both coasts before tending variable into the afternoon.

Therefore Sunday is more than worth heading down South for a solid clean and easing S/SW swell.

Monday should be even better as a slightly stronger offshore N/NE wind irons out any wobbles/lumps in the swell as it continues to ease.

A low point in swell activity is due into Tuesday under strong and unfavourable N/NW winds, but from Wednesday onwards we should see medium to large pulses of SW groundswell impacting the state. This will be related to another strong amplification of the Long Wave Trough moving in from the west, but we'll look at this more on Friday.