Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 30th December)

Features of the Forecast (tl;dr)

• Small average waves through the rest of the week
• Easing onshores into Thurs, freshening again Fri, easing back over the weekend
• Building mix of swells from Friday PM into the weekend, becoming quite fun as winds lighten
• Plenty of surf next week, of varying quality. No major size, but still some potential to keep an eye on

Recap: Tuesday offered small, slow waves with early light offshore winds swinging light to moderate S/SW through the day. Freshening onshore winds from the SE today have accompanied a small rise in local swell to 2-3ft, though quality has been lacking.

This week (Dec 31  - Jan 1)

The main driver for today’s onshore breeze is the squeeze between a trough off the Mid North Coast, and a high pressure system in the lower Tasman Sea. The high will ease overnight, relaxing the pressure gradient and allowing the onshore flow to ease, so conditions will slowly improve. 

However because most of today’s surf is locally generated, wave heights will concurrently throttle back. I’m also downgrading the potential for a secondary E/NE trade swell over the coming days, as its performance across Northern NSW has been a little under spec over the last 48 hours. 

As such, expect peaky 2ft sets across open beaches on Thursday with light and variable winds tending light to moderate onshore for periods throughout the day. It’ll be surfable but nothing special.

On Friday, a new high pressure system will move up from the southern Tasman Sea and gradually freshen onshore winds across the coastal margin, however most of the strength will probably be contained between Sydney and the Hunter region, with lighter winds south from the Illawarra. There’s a reasonable chance for periods of light variable winds in the early morning too. 

Wave heights will probably remain around there 2ft mark, but should increase into the afternoon with additional windswell, perhaps nudging 2-3ft (mixed in with the small trade swell too). But again, keep your expectations low for any quality. 

This weekend (Jan 2 - 3)

The trough off the Mid North Coast will merge with a broader trough across the inland region into the weekend, initially pulling south before pushing eastwards into the Tasman Sea overnight Sunday and into Monday. 

This creates a tricky weekend in the wind department, with winds likely to become variable - probably through Saturday - before potentially freshening from the north at some point into Sunday ahead of a return southerly flow overnight into Monday.

The models are split on the timing and precise location of these developments, so confidence is presently low - however I’ll have a better idea in Friday’s update. 

What’s a little more clear for the weekend is the likely swell, as a freshening E’ly fetch in the central Tasman Sea - feeding into the merged trough - should be far enough off the coast to favour most regions with building short range swell, biggest on the South Coast though with a great risk of onshore winds (south from about Ulladaulla) across the southern flank of the trough.

Nevertheless, for Sydney, Hunter and Illawarra coasts we should see surf size building from 2-3ft to 3-4ft throughout Saturday, holding Sunday. The Far South and South Coasts should see another foot, maybe two on top of this. There’ll also be a persistent small spread of trade swell in the mix too.

I’ll firm up the local winds in Friday’s outlook, but there’s certainly potential for reasonable waves both days. 

And, late Sunday is still on the cards for a pulse of new SE swell form a small low off the SW tip of New Zealand’s South Island, however Monday is a better chance for this.  

Next week (Jan 4 onwards)

Southerly winds are on the cards for Monday, originating from the western flank of the new low in the Tasman Sea, formed in the wake of the weekend’s trough. 

At the moment the models are split on its strength and duration within our swell window, so I’m reluctant to commit to a size right now, but either way it’ll be a change from the unstable troughy pattern of late. There is certainly some local south swell potential early next week though.

Otherwise, Monday will deliver a mix of swells out of the SE (originating from the low off NZ - models have eased its strength since Wednesday, but aligned it a little better in our swell window), with inconsistent 3ft sets to exposed beaches, plus a mix of trade swell (from the northern Tasman Sea), fading E/SE swell (from the bottom of the weekend’s trough) and some short range N/NE swell from a coastal ridge across Northern NSW on Sunday. Complex, eh?

The SE swell from NZ will fade rapidly through Tuesday but the rest of the week will see continuing E/NE swell thanks to an ongoing ridge lying north of New Zealand. Its orientation through the Tasman Sea may be tweaked just out of our swell window as Monday’s low navigates eastwards, but at this stage I’m expecting residual 2-3ft sets through into the middle of next week at least.

And, depending on how the Tasman Low develops on Monday, we’ll may have another day or two of S'ly tending SE energy from this source. 

So, the long and short suggests plenty of surf for next week, most of it on the small side and sometimes wind affected, however lingering troughiness through the Tasman Sea will hold potential to regenerate a significant swell generating system. It’s not showing anything significant on the charts right now but certainly can’t be ruled out.

And thus we wait for Friday’s update, for (hopefully) signs of a more sizeable swell mid-late next week.

See you then!