Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 22nd August)

Best Days: Sat/Sun: fun peaky waves at the open beaches. Mon/Tues: building E/NE swell, but with dicey winds. Wed/Thurs/Fri: large E/NE swell, but with dicey winds.

Recap: Moderate SE tending E/SE swell with early light offshores tending onshore during the day.

This weekend (Aug 23-24)

Still no changes to be made to the weekend forecast. We’ve got a handful of swell sources expected to generate peaky waves across most open beaches both days, and high pressure over the region should create generally light variable winds (offshore early, onshore from late morning onwards).  

The primary swell source is a broad but only moderate-strength easterly fetch occupying the northern half of the Tasman Sea, across the top of a high pressure system that’s developing in the southern Tasman Sea today. No major size is expected overall but most open beaches should see peaky sets in the 2-3ft+ range. Certainly not perfect but well worth a paddle. 

Next week (Aug 25-29)

Jeez we’ve got a dynamic period of waves on the cards next week. As has been discussed since last Monday, the synoptic outlook has the Tasman High interacting with a broad area of low pressure in the southern Coral Sea from the weekend onwards.

Model guidance is now much more confident on the development of an easterly dip/trough off the southern Qld coast that could very well develop into a full-fledged East Coast Low as it migrates southwards, parallel to the coast.

The implications of this scenario are quite broad and far reaching. Initially, the easterly indeed into the trough/low will itself generate a healthy E/NE for southern NSW with a steady upwards trend expected from Monday onwards. 

However, if the low strengthens as is currently modelled, we could see some very large, windy waves across southern NSW mid-late week (Wed/Thurs/Fri). It’s too early to have confidence in just how much size right now but early indications are in the 8-10ft range, possibly bigger. This will however depend on the positioning and track of the trough/low.

That being said, such a swell is also likely to be accompanied by easterly gales and heavy rain (with winds becoming lighter in the south of the state). So, surfing conditions are likely to be tricky at best. 

One area to focus on next week will be the expected position of the trough’s axis. The reason being is that locations north of this point will see an outflow from the SW, creating clean conditions. The models are split on where this may be - right now there’s not much chance of it tracking any further south than about Seal Rocks - however it’s worth remembering that this situation is under continual revision as the models hone in on the specifics (and Wednesday really didn’t have this scenario mapped out at all).

So, we may see some very interesting possibilities crop up over the weekend with future model updates. And if you've got some flexi time up your sleeve it'll probably be well worth a road trip to the north.

Either way, this pattern is expected to dominate the swell window right through until the weekend. I’ll be very interested to see what Monday's updates brings.

Longer term (Aug 30 onwards)

Right now I can’t find any reason not to suggest that the mid-late week E/NE swell won’t hold - even if in a reduced format - through next weekend. The expected slow moving nature of this pattern suggests a long lived swell event that’ll generate waves from south-eastern Tasmania to Fraser Island, and there’s bound to be some excellent surf at some point throughout the longer term period. Tune in on Monday for more details.