Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 6th September)

Best Days: Sat: very clean but small. Sun: flukey though solid S'ly swell, clean with fresh offshore winds. Mon PM/Tues: very large but very windy. Wed: solid, easing but clean mix of swells from the S/SE thru' E/SE. Thurs/Fri: interesting long period S'ly swell. 

Recap: Thursday maintained fun E’ly swells in the 3ft range, with offshore winds and afternoon sea breezes. Size eased back to 2ft+ this morning, though has rebuilt to 3ft+ this afternoon with a peaky NE windswell, however conditions have been bumpy with the accompanying NE winds. A late W’ly change is imminent. 

Lumpy NE windswell at Manly mid-late afternoon (pre-W'ly change)

This weekend (Sep 7 - 8)

The W’ly change will quickly erode our local NE windswell, so with eleven hours under the cover of darkness for the easing trend to do its thing, I’m not expecting a great deal of leftover energy early Saturday morning. A strong secondary N’ly fetch off the Northern NSW Coast just starting to develop this afternoon, though its poorly aligned for our coast, so I'm not expecting much from it either,

So, we’ll see small peaky leftovers first thing but don’t expect much size. It will however be super clean with fresh offshore winds. 

A deepening low pressure system east of Bass Strait tonight has slowed a little in the model runs since Wednesday’s outlook, and we’re now looking at the strongest fetch developing late Saturday afternoon, which means a building trend for Sunday.

On Saturday, I’m really not confident that we’ll see much new S’ly swell, because most of the wind to our south will be W’ly, perpendicular to our southern swell window. There’s certainly a chance for a couple of stray feet getting into south friendly beaches (Hunter region the greatest prospect of this, maybe 2ft+ from time to time?) but on the balance I think it’ll be very small just about everywhere for much of the day. 

Saturday’s late fetch existing eastern Bass Strait will remain poorly aligned within our swell window (see below), however with core wind speeds of 50-60kts, we’ll see some large surf building into Sunday with south facing beaches likely to see 5-6ft+ sets, pushing 6-8ft+ across reliable south swell magnets such as the Hunter region.

Our surf model is showing a peak in size late afternoon, but I have a feeling it’ll arrive earlier than this, before lunchtime - regardless, it'll be sizeable all day. The swell direction will be acutely south so expect significantly smaller surf elsewhere. Conditions will be clean, though blustery with fresh W/SW winds. 

Next week (Sep 9 onwards)

Wave heights will trend down rapidly into Monday morning, but at the same time, a brand new front will cross the southern Tasman Sea, generating S’ly gales adjacent the South Coast (see below).

As a result, we’re looking at large S’ly swells kicking in during the afternoon, peaking overnight and holding most of its size through Tuesday morning before trending down into the afternoon and then easing rapidly throughout Wednesday. 

Surf size should peak in the 8ft+ range at most beaches with good southerly exposure, though with the gusty southerlies, only sheltered southern ends will have workable options where surf size will be a lot smaller.

There’s a chance for a brief window of SW winds at one or two regions early Tuesday, but this is low confidence because the strength of the southerly synoptic flow looks to be pretty strong (and will probably override the terrestrial influences). It'll be quite a messy, disorganised swell compared to Sunday's event. 

Wednesday will see the swell direction veer S/SE through SE, thanks the low moving north on Tuesday, allowing its southern flank to become the primary influence. We’ll also see a smaller secondary E/SE swell in the water, from a brief fetch exiting Cook Strait on Monday (you can see in the image above). Set waves should manage 5-6ft early (mainly south facing beaches) but expect size to ease throughout the day. 

Wednesday’s main positive is that winds will ease quickly as the low moves away form the coast, so we’ll see lighter W/SW breezes in the morning. 

Thursday looks much smaller though very clean, with light offshore winds and easing swells from Wednesday.

However - and, the models are not picking this up yet - a long period S’ly groundswell is expected to push along the Southern NSW coast, generated by a large, powerful low tracking south of Tasmania on Tuesday (see below).

Leading edge swell periods should be in the 18-20 second range, and we’re looking at a late peak (holding into Friday morning) with 3-5ft surf at south facing beaches, possibly nudging 6ft+ at one or two reliable south swell magnets. It’s a flukey swell direction so will bypass quite a few beaches but there’ll be good options to finish the working week. 

The only concern with Friday is that an unrelated front is on the cards to clip the Southern NSW coast and this may play havoc with local winds (and also generate a mid-range S’ly swell that could create unusual doubleups with the pre-existing S’ly groundswell).

Anyway, I’ll firm up all of this on Monday. 

Have a great weekend!