It's been an active late autumn and early winter across much of Australia, with great waves on many coasts. 

On the other side of the planet, South Africa is being slammed by a severe storm that generated huge damaging swells and 100km/hr+ winds that are fanning wild fires around Knysna in the Western Cape Province (picture source: Twitter).

This storm is also set to deliver large swells to Skeleton Bay, with crews descending on the Namibian coast from all over the world as we speak.

More interesting to us in Australia and anyone travelling to Indonesia next week is that the storm currently impacting South Africa will track south-east, weakening temporarily before firing back up in a big way, west of Heard Island - longitudinally midway between Africa and Australia.

This re-intensification will be linked to the storm feeding off a pronounced node of the Long Wave Trough just south-east of Madagascar.

Model predictions have an expansive fetch of severe-gale W/SW winds projecting east along the polar shelf, with stronger storm-force (55-60kt) winds at its core.

This will set in motion a large long-period groundswell event for the southern Australian coast alone, but a secondary intensification of the storm once east of the Heard Island region will see an additional fetch of severe-gale W/SW winds projected towards Western Australia, working on top of the large active sea state.

A super-charged open ocean swell is expected to develop, resulting in XXL waves across the South West coast of Australia and XL surf for South Australia, west facing coasts in Victoria and Tasmania, plus a very large swell for the Indonesian archipelago.

We should see the swell arriving through Tuesday across WA, building rapidly into the afternoon ahead of a peak Wednesday. Indonesia will see the swell building rapidly Thursday ahead of a peak overnight/early Friday morning.

Size wise we're looking at 18-20ft+ surf across offshore reefs and bommies in Margaret River, smaller towards South Australia, while Indonesia should see surf peaking in the 10-12ft+ range.

Winds are still varying a little for Western Australia but S/SE breezes are more than likely, while SA will see more favourable N'ly breezes. Keep an eye on each regions forecaster notes over the coming days for more specifics regarding the timing, size and conditions for this swell.