Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 16th September)

Best Days: All week: plenty of swell from a wide variety of source, but local winds will create problems most days. Thursday morning looks to have the best conditions overall, and Saturday may throw up some options, otherwise it's slim pickings right now.

Recap: The weekend delivered a mix of S’ly swells, though there was a wide range in size across the coasts, and swell direction seemed to be more S/SE, even SE at some beaches. We saw 4-5ft+ sets at a handful of south swell magnets (mainly Newcastle region early Sunday) whilst south facing beaches across the Sydney region peaked around 3ft+, with smaller surf elsewhere. Saturday saw a deterioration of conditions as a southerly change pushed up the coast but Sunday morning was clean with offshore winds ahead of an afternoon sea breeze. Size eased back a little more today and early offshore winds have preceded a S’ly change, currently gusting 36kts at Bellambi.

Early Monday peaks in Newcastle

This week (Sep 17 - 20)

We’ve got an enormously diverse range of swell sources for the coming week and a half.

Today’s southerly change won’t generate much more than a short lived windswell for Tuesday, but the parent front well to the south was quite strong and should kick up 4ft of south swell that fill in underneath a freshening onshore breeze as a trough stalls off the Mid North Coast, and directs SE winds into the Southern NSW coast.

A low will form along the trough line during the day, strengthening the SE fetch along its southern flank, building SE swells through the afternoon and into Wednesday where we’ll see a peak in size easily around the 6ft+ mark, closer to 6-8ft+ across the Hunter region where the fetch will be mostly aimed.

Of course, fresh SE tending S/SE winds will maintain poor conditions just about everywhere, so keep your expectations low for any quality. Surf size and wind strength will however gradually taper off as you head south from the Illawarra.

The low will weaken into a broad coastal trough again by Thursday, allowing lighter, more variable (possibly early SW) winds and improving conditions, and a mid-week E/NE infeed into the trough will rebuild moderate swells from the same direction as the local SE swell eases. Thursday will see a mix of energy abating from 4-5ft to 3-4ft, Friday will see the E/NE swell dominate around 3-4ft or so. Onshore winds out of the NE are likely as an approaching front from the south-west tightens the pressure gradient (building an additional local windswell to 4-5ft late Friday afternoon), but wind speeds shouldn’t be too strong for most of Thursday and early Friday. 

It’s also worth mentioning that this week will concurrently experience a series of overlapping long period S’ly groundswells, generated by a succession of incredibly powerful lows below the continent at the moment. 

Peak swell periods could very well top out at 20+ seconds a couple of times in the coming days, but these swells will be smaller in size than the local events, and to be honest, confidence is not high on how much size we’ll see because of their remote, flukey origins. But, it’s possible one of those days (I’m thinking later Thursday or Friday) could occasionally nudge 3-5ft at south swell magnets like the Hunter. 

In any case, the presence of the local swells, alongside generally poor local conditions will render this unusually long period S’ly swell somewhat useless, which is a shame.

This weekend (Sep 21 - 22)

The main synoptic feature for the weekend is a shallow trough that’ll cause a wind shift from the north to the south, later Saturday afternoon on the South Coast and into Sydney overnight.

Friday’s mix of rebuilding E/NE swell and NE windswell should hold out for Saturday in the 4-5ft range but local N'ly winds will probably maintain below-average conditions. There's a chance for a brief period of NW winds but confidence is not yet high on this.

By the time the S’ly change kicks in on Saturday evening, the swell source will have started to weaken and therefore Sunday morning is looking at much smaller leftover NE swells, perhaps 2-3ft but easing to 1-2ft during the day, along with a small local southerly windswell through the afternoon. But quality won’t be high owing to associated fresh southerly winds. 

Let’s take a closer look on Wednesday when we can assess the winds in more detail.

Next week (Sep 23 onwards)

Our local NE airstream later this week will be associated with a broad high pressure system in the eastern Tasman Sea, which will also display a broad easterly fetch off its northern flank (see below).

This is expected to generate a small though reasonably long-lived trade swell, filling in underneath the weekend’s local noise and persisting through until about Tuesday or thereabouts. No major size is expected but the start of next week should see a few stray 2ft sets at exposed beaches, plus some small lingering S’ly swell from Sunday.

Otherwise, beyond this there’s nothing more than the usual frontal progression through our south swell window.

More in Wednesday’s update.