Long period south swell for the weekend; solid south swell(s) next week

Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 21st September)

Best Days: Sat: building long period S'ly swell in the a'noon, though winds may spoil conditions. Sun: chance for a pocket of OK winds in the AM with easing S'ly swells. Mon PM/Tues: plenty of south swell, improving conditions. Wed PM/Thurs: solid, long period S'ly groundswell.

Recap: Wednesday’s tasty NE swell eased rapidly into Thursday, and a building south swell was made bumpy with mainly moderate to fresh S’ly winds (though they eased into the afternoon). Wave heights reached around 3ft throughout the day, and have eased in size today though early morning was still producing some nice waves across Hunter beaches around 3ft+ (see surfcam image below from Newcastle, early morning). Surf size is now much smaller and the sea breeze is up from the E/NE.

Newcastle earlier Friday
This weekend (Sep 22 - 23)

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We’ve got a tricky weekend ahead, though there is plenty of potential.

A southerly change is expected to dominate the region on Sunday, and although there’ll be plenty of south swell in the water, exposed beaches are likely to become bumpy and wind affected.

Saturday will start off very small, with light winds. The leading edge of a new long period southerly swell is expected to push into the South Coast early morning, reaching Sydney late morning or lunchtime, before building through the surf zone into the afternoon. This swell was generated by an intense low in the Southern Ocean below South Australia mid-week, and the swell has already reached Tasmania and Victoria with some impressive waves reported across these coasts.

The low responsible for the swell was poorly aligned within our acute south swell window, but it was quite far to the south, and contained within a very broad, elongated fetch of westerly gales, which will assist in pushing the swell up along the NSW coast. 

We’re likely to see a wide range in wave heights owing to the acute swell direction and the large swell periods (Pt Nepean in Victoria recorded the leading edge at 22 seconds) - so as much as I don’t like to sit on the fence and throw out broad size estimates, the truth is that we’ll see significant variations in wave heights from coast to coast, and even beach to beach.

Ballpark size range is still for a peak around 3ft+ at most south facing beaches, pushing 4-5ft at reliable swell magnets and across the Hunter. However, I wouldn’t be surprised if we saw an embedded pulse very late Saturday that nudged a little higher than this for an hour or so (likely mid-afternoon on the South Coast, late afternoon Sydney/Hunter coasts). It will however be much smaller elsewhere.

Winds will be up from the N/NE by this time so you’ll have to duck into a sheltered northern corner anyway. Expect smaller (and by this time, much bumpier) surf at southern ends. 

Saturday’s swell will ease steadily through Sunday, and the models have slightly delayed the bulk of the strength in the southerly change - we’ll see moderate southerly winds through the morning and lunchtime period, becoming fresh to strong mid-late afternoon. There is a chance that we’ll see periods of lighter SW winds at times (mainly a few select coasts such as the Northern Beaches) but I don’t think we’ll see any appreciable windswell until Monday. Perhaps a foot or two through the day, with a lake kick once the southerly ramps up. But quality won’t be that great.

As such, Saturday afternoon is still the pick of the weekend, if you can tuck into a sheltered northern corner that enjoys long period south swells. Keep an eye out for Sunday morning too.

Also, just to confirm that the weekend will see a small undercurrent of long range E/NE swell generated by a broad subtropical low NE of New Zealand. Unfortunately it was positioned quite some distance back in the South Pacific but we should pick up a few small stray sets both Saturday and Sunday, though it won’t be worth getting too excited about.

Next week (Sep 24 onwards)

Sunday’s late burst of southerly wind will ease through Monday but likely linger about the coastal margin through the morning, leaving us with lumpy/leftover surf. 

We’ll see a bumpy mix of south swells in the 3-4ft range at south facing beaches to begin the working week. However, the percentage of windswell / groundswell will swing back in our favour later Monday and into Tuesday as a new southerly groundswell pushes into the coast, originating from another poorly aligned front south of Tasmania on Sunday (related to the southerly change). This should keep south facing beaches holding somewhere between 3ft and maybe 3-4ft, with larger sets across the Hunter region, though smaller waves at beaches not open to the south.

Tuesday’s swell will then ease into Wednesday morning, but will then be overtaken by a series of long period southerly swells related to an amplifying node of the Long Wave Trough across the Southern Tasman Sea. 

Unfortunately the models have moved things around a little since Wednesday’s Forecast Notes were prepared, but we’re still looking at a solid event building Wednesday (likely the afternoon) and peaking on Thursday morning with sets in the 5-6ft range at south facing beaches. The large periods associated with this event should exacerbate wave heights at deep water bombies and other reliable south swell magnets such as the Hunter region (perhaps another 30% on top).

Current expectations are for winds from the NW thru’ N, but we’ll refine this in Monday’s notes. 

Looking further ahead and moderate though still quality S/SE swells (related to the same LWT) will play out the end of next week, holding into the weekend, whilst there’s also some out-of-season tropical activity suggested for the tropics near Fiji that may bring about a NE or E/NE event midway through the following week.

Have a great weekend!


jbrowne's picture
jbrowne's picture
jbrowne commented Friday, 21 Sep 2018 at 5:34pm

Hi guys do you think the early Sunday will be blown out between say the illawarra and cronulla on account of the southerly? I mean the early early from 530 to 730.

thermalben's picture
thermalben's picture
thermalben commented Friday, 21 Sep 2018 at 6:04pm

Can't really provide much more detail than the above right now mate, sorry.

jbrowne's picture
jbrowne's picture
jbrowne commented Friday, 21 Sep 2018 at 6:10pm

No worries! Ill keep an eye on everything, and hedge my bets letting the missus get her sleep in tomorrow rather than Sunday :)

thermalben's picture
thermalben's picture
thermalben commented Saturday, 22 Sep 2018 at 6:10am

There we go! 19.28 seconds detected at the Port Botany buoy around 5:20am. A few hours earlier than expected, which is a good thing as it means the upwards phase will arrive earlier too - hopefully before the NE breeze kicks in.

peter kelaher's picture
peter kelaher's picture
peter kelaher commented Saturday, 22 Sep 2018 at 4:50pm

More on that long range north east swell as I am hitting snapper wed 3 rd oct

Glassy conditions