Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 3rd October)

Best Days: Local winds will largely spoil conditions most days, which is a shame as there'll be stacks of swell. 

Recap: We’ve seen a fun mix of NE windswell and long period S’ly groundswell over the last few days, with size around 2ft+ across south facing beaches, bigger across the Hunter around 4ft. Winds were light early Tuesday but freshened from the N/NE throughout the day. Lighter winds have held out of the N thru’ N/NE today.

This week (Oct 2 - 5)

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There a lot to digest in today’s forecast notes. First of all, let’s discuss peripheral energy for the rest of the week.

We’ve got three sources contributing energy - minor NE windswell from a weakening fetch off the Mid North Coast, slowly building small to moderate E/NE mid range swell from a broad though otherwise unremarkable trough south of New Caledonia over the last few days, and a series of overlapping long period southerly groundswells generated by an intense progression of fronts and lows below the continent. 

The main energy of any note from these three is the southerly groundswell, which should display peak swell periods of 19-20 seconds later Thursday or early Friday. However it's unlikely you'll be able to notice all of this energy above the local noise. 

What’s going to affect our surf much more prominently is a developing trough off the South Coast that’s expected to form a closed system during Thursday, possibly a Tasman Low (just an outside chance for an ECL now). 

A southerly change associated with this pattern is already encroaching the Far South Coast, and should reach the Illawarra by the early hours of Thursday morning, pushing north into Sydney a few hours before dawn and then nosing into the Hunter around sunrise.

By and large, winds will be fresh southerly through Thursday tending south-east throughout the day. There’s a chance for pockets of early SW winds but I wouldn’t hold your breath. So, southern corners will be your only option.

We’ll also see a building local swell in the lee of the change but no major size is expected until overnight Thursday, which is the time frame when I thought we may see a small ECL develop off the Hunter, along the stalled trough line. Indeed, model guidance strengthens SE winds to 30kts+ through this period and it’ll create a rather terrible round of surf conditions on Friday under strong to gale force S/SE winds. 

Maximum surf size will be concentrated in and around the zone of the strongest winds (i.e. north from Sydney) and we could see stormy 6-8ft surf here on Friday. However, most other coasts are looking at a smaller combination of swells, anywhere between 4ft and maybe 6ft depending on your beach's exposure. Locations south from the Illawarra will probably see slightly less size. 

But seriously, with these winds conditions won’t be worth getting too excited about at many coasts.

This weekend (Oct 6 - 7)

Friday’s low-of-some-description will move slowly north into the weekend, though we’ll see lingering fresh southerly winds across the coastal margin into Saturday, maintaining average to poor conditions across most open coasts. 

In fact, depending on your preferred model guidance, we could very well see fresh southerlies persist into Sunday as a secondary low develops at the tail end of the trough in the Central Tasman Sea (on Saturday, see chart below) and pushes back towards the Southern NSW coast.

Either way, swell won’t be in short supply. We’re likely to see continuing SE swells in the 4-6ft range for Saturday, easing into Sunday, and there’ll be an appreciable level of mid-range E/NE swell from Friday (persisting all weekend) plus some small underlying long period S’ly groundswell. 

It’s just these local winds that will cause problems. Southern ends and sheltered points should be clean although much smaller. Pockets of early SW winds are possible though only at a handful of coasts at best (Northern Beaches the most likely contender, again).

Next week (Oct 8 onwards)

Model guidance is still too divergent for any confidence in the long term outlook, however the broad picture suggests a weakening influence in the Tasman from the weekend’s system, followed by a resurgence from the south early-mid-next week that could deliver a sizeable southerly groundswell. More on this in Friday’s update.