Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 27th December)

Best Days: Average conditions for the few days, but there'll be bumpy waves on offer. Wed onwards: lighter winds (mainly out of the south) and an extended run of small to moderate cyclone swell (it'll arrive early in the week but local winds look average Mon/Tues).

Recap: Small swells and NE winds haven’t offered much in the way of quality surf across Southern NSW over the last few days.

This weekend (Dec 28  - 29)

No change to the weekend forecast. 

A slow moving high pressure system in the Tasman Sea will maintain moderate to fresh NE winds across most coasts all weekend, in fact they’ll persist until Tuesday. 

A weak trough will push into the Far South Coast very late on Saturday, disrupting the N’ly flow and we’ll see its influence spread north to about Wollongong overnight. N/NE winds will persist through Sunday though a little weaker in strength, and anywhere south from the Illawarra should see light variable winds at times on Sunday, mainly early in the day.

Both mornings may see isolated patches of light winds across the Sydney, Hunter and Illawarra coasts though given the previous days onshores, surf quality is unlikely to be especially high.

As for surf, there’s nothing major expected. We’ll see a small combo of swells both days, originating from a poorly aligned front south of Tasmania Thursday (S’ly), some small distant trade swell from the South Pacific (E/NE) and Northern Tasman Sea (E/NE) but the largest swell source will be local NE windswell from the strengthening fetch adjacent the coast. 

Saturday morning may be undersized, but we’ll see bumpy 2-3ft surf across most NE facing beaches by the afternoon and into Sunday. Because of the way the fetch develops, late Saturday should see slightly larger surf south from the Illawarra, and with a few possible options for a late glass off in the Far South, there could be a nice window of punchy waves in this neck of the woods.

Otherwise, expect the wind to spoil the surf elsewhere.

Next week (Dec 30 onwards)

Restrengthening NE winds on Monday will rebuild NE wind swells into the afternoon and Tuesday, reaching 3ft, maybe even 3-4ft at times though quality will remain average for the most part under the accompanying NE breeze. 

On Tuesday afternoon, a trough will push up the coast, bringing a southerly change to some regions though it’s currently unclear how far north it will track before the end of the day (most likely scenario is about the Illawarra). It should however envelop the Sydney region into Wednesday. There’s a chance for a period of favourable winds on Tuesday depending on how the trough behaves but we’ll have a better understanding of this on Monday. It's more likely to occur on the South Coast. 

Whilst all of this is going on, a brand new NE tending E/NE cyclone swell will have started to filter down the coast, generated by TC Sansai which is currently north of Fiji, inside our swell shadow. It’s expected to push into our swell window by tomorrow, though will initially be unfavourably setup for our region.

In fact, despite a slow track over the coming days at (likely) Cat 2 strength, the core of its lifespan fetch will be mainly aimed away from Southern NSW. What’s in our favour is its slow forward speed and its lengthy duration within a reliable part of our swell window. This should help to generate a decent spread of E/NE swell that I’m expecting will push much higher across Southern NSW than model guidance is suggesting.

Current expectations are for a small, slow building trend through Mon/Tues (beneath the larger local NE windswell), but as this short range source subsides from Wednesday under the southerly breeze, we’ll see several pulses of E/NE swell dominate the second half of the week. Set waves will be inconsistent, and it’s worth noting that instead of a the more common, defined swell trend (quickly up, then a brief plateau, then a slow but steady decline), we’re looking at intermittent pulses probably holding into next weekend.

Peak surf size is expected to reach 4-5ft, in fact I wouldn't be surprised if one or two swell magnets produce larger bombs in the 4-6ft range - core winds within the cyclone are expected to be very strong (see below) so swell periods should be up around the 14-15 second mark (better aligned coasts to our north should see slightly larger swell periods and thus larger surf). Wednesday is the best chance of the upper end of this size range occurring though we could see brief strong pulses later in the week (though in general it’ll generally be a little smaller and less consistent).

As for conditions, the late Tuesday trough/southerly change will stall and linger about the region, probably keeping us under a light to moderate southerly flow but with pockets of lighter, more offshore winds, mainly through the mornings. There will be an onshore threat for the entire period though, as is always the possibility under unstably, troughy patterns.

As a side note, we'll see some small southerly swells later next week from a series of porly aligned Southern Ocean fronts below Tasmania Tues/Wed, but no major size is likely and the cyclone swell will certainly be the dominant energy in the water.

Either way, we’ve got plenty of surf in store for next week - you’ll just have to work around the winds. 

Have a great weekend, see you Monday!