Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 27th September)

Best Days: Thurs: fun NE swell early, easing during the day. Fri: light winds and a fun small south swell. Sat/Sun: building S'ly swells, biggest Sunday. 

Recap: Tuesday dished up some fun southerly swell with 2-3ft sets at south facing beaches and bigger waves across the Hunter. This swell has slowly eased today and NE winds have freshened, with NE facing beaches seeing a late increase in short range windswell (as per the image below). 

Building NE swell across the Manly stretch late this afternoon

This week (Sep 26 - Sep 29)

This afternoon’s strengthening NE winds will reach a peak overnight, generating a solid short range NE swell that should manage early 3ft+ sets across NE facing beaches at dawn on Thursday. However, a moderate W’ly change is expected in the early hours of Thursday morning and this will both clean up surface conditions but also shut off the swell supply to the coast, leading to a steady downwards trend from the get-go.

As such, we’re looking at much smaller conditions by Thursday afternoon and you’ll have to surf early for the best waves. It’ll be nice and clean on the surface though. Light afternoon sea breezes are possible. Expect smaller surf from this source at beaxches not open to the south, and across the northern Hunter coast.

Northerly winds will persist off the Northern NSW coast on Thursday, and although generally well off-axis from our swell window, should allow some small waves to persist into Friday at exposed NE facing beaches (no more than a lazy 1-2ft though). 

We’ll concurrently see a small S’ly swell push up the coast, generated by a front tracking east of Tasmania on Thursday. The latest models have weakened this fetch so I’ve slightly downgraded size expectations to 2ft+ at south facing beaches (bigger in the Hunter near 3ft+). 

Interestingly, the models are now showing two seperate S’ly swell trains for Friday - the short range energy mentioned above, but an additional long period swell that’s actually expected to reach the coast on Thursday with peak swell periods of 15-16 seconds. 

This (modelled) long range southerly energy slipped through the net in Monday’s forecast notes, probably due to the models showing a stronger post-Tasmanian frontal system (and thus masking the source). However without enough time to do a proper hindcast, I’m going to discount it as a notable swell source - Craig mentioned this swell in his Victorian notes today but it’s only generated 2ft+ surf across the Torquay stretch and is therefore unlikely to kick up much size across the Sydney region due to the further travel distance and even less favourable coastal alignment. 

It is however hard to completely ignore - for example, noon on Friday has the long range swell of 0.6m @ 12.7 seconds, plus the (aforementioned) mid range energy of 0.7m at 9 seconds. Both swells should be worthy of somewhere between 2ft and 3ft at south facing beaches but we’ve had plenty of instances in the past where deep polar lows (such as the one responsible for this modelled long range swell) have punched well above their weight. As such, we’ll just have to wait and see what happens - but on the balance I’m in favour of the surf being generally small out of the south. 

Conditions will remain clean with early light offshore winds and an afternoon sea breeze. 

This weekend (Sep 30 - Oct 1)

The models have slightly weakened the approaching frontal system for the weekend’s south swell, compared to Monday. It still looks very large and quite strong, but most of the primary fetch won’t be very aimed within our swell window.

The intense polar low (a long period source for Sunday) has also been shunted slightly west out of our swell window, which diminishes the size potential for Southern NSW.

Regardless, at the moment I think our model is undercalling this swell. We’re looking at small residual swells on Saturday morning, building to 2-3ft+ at south facing beaches into the afternoon, holding at this size into Sunday morning ahead of a slightly kick to 3-4ft on Sunday afternoon as the long period energy fills in. Expect bigger surf across the Hunter but smaller waves at beaches with less southerly exposure. 

No major strength is expected in the wind field each day so we’ll see generally favourable conditions.

Next week (Oct 2 onwards)

Strong frontal activity through the Southern Ocean will maintain small to moderate southerly energy through the early part of next week, ahead of a vigorous front expected to track through the lower Tasman Sea later Tuesday that should set up a bigger south swell for later Wednesday and Thursday.

I’ll also be keeping a close eye on a small stationary polar low off the ice shelf, directly south of new Zealand early-mid next week, that may kick up a small long period S/SE groundswell for the end of the week. 

More on this in Friday’s notes.