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

Best Days: Thurs thru' Mon: mix of mainly small swells from the southern quadrant, but with tricky winds (aim for early mornings). Tues/Wed: solid E/SE swell with (at this stage) good winds. Next Thurs/Fri: easing but still good E/SE swell, with possibly a second stronger SE swell in the mix.

Recap: Tuesday’s swell combo generally fell inline with expectations although the NE windswell component was a slow grower. Early morning started out with inconsistent 2ft sets from the NE and some leftover S’ly groundswell in the 2ft range, but by mid-late morning NE swell magnets were seeing occasional 2-3ft sets. Winds gradually swung from the N to the NW ahead of a late S’ly change. Today we’ve seen a fresh S’ly swell (originating from the parent low associated with Tues’ late change) push into the coast and set waves are a good 3ft at south facing beaches. Winds were light offshore through mid-morning before swinging moderate to fresh SE for the rest of the day.

This week (Sep 17 - 18)

A trough pushing off the NSW coast today and a high ridging in from the west are expected to drive fresh southerly winds across much of the East Coast for the next few days.

The coastal trough will stall off the Far North Coast - possibly forming a small closed low east of Byron Bay on Friday - but a series of approaching fronts into the Southern Tasman Sea will anchor this southerly airstream in place for a while.

Whilst the local fetch won’t generate much new swell for the coast, we still have plenty of energy on tap for the short term forecast period. Today’s south swell will ease through Thursday but it’ll be replaced by a small long period southerly swell, generated by a series of intense lows through the Southern Ocean over the last few days. This combination should maintain inconsistent 2-3ft sets at south facing beaches on Thursday. However apart from a few hours of early W/SW winds, most of Thursday (from mid-morning onwards) is looking at bumpy conditions under a fresh southerly breeze. Locations protected from these winds will be much smaller.

Another pulse of long period south swell is expected on Friday, much in the same vein as what’s due Thursday, but we may see a little more short range energy and consequently slightly bigger sets are possible at swell magnets. But for the most part local winds look pretty shabby - only the early morning has any chance of a brief window of opportunity of more favourable winds (and even then it’ll be restricted to just a handful of locations such as the Northern Beaches).

So overall, there’ll be waves for the next few days but don’t expect any major quality.

This weekend (Sep 19 - 20)

We’ve got a couple of swell sources for the weekend. The final pulse of southerly groundswell from the current pattern will provide Saturday morning with similar surf to Friday (occasional 2-3ft sets south facing beaches, smaller elsewhere) and local winds are looking to hang from the S/SE for much of the day - albeit weaker than what we’re expecting on Friday. So, early morning should have a period of light W/SW winds across many regions but swell quality probably won’t be especially high. An easing swell trend is likely into the afternoon too, and the surf will be smaller at beaches not open to the south.

Sunday looks a little more interesting. On Friday, a small low is expected to form off the West Coast of New Zealand’s South Island, strengthening a S/SE fetch that’ll supply a fresh swell for Southern NSW later Sunday and into Monday. A ridge of high pressure in the southern Tasman Sea is expected to concurrently extend the head of the fetch into the central Tasman (on Saturday) and we’re looking at a corresponding bump in short range E/SE swell throughout the day.

The morning is likely to start out smaller with residual swells from Saturday across exposed beaches, but through the afternoon we may see some 2ft to maybe 3ft sets across most open beaches. Local winds look like they’ll be mainly light and variable; the most likely pattern being early onshore and afternoon onshore - but without any major strength. So, this should provide plenty of options for the beaches through Sunday. I’ll firm up the specifics in more detail on Friday.

Next week (Sep 21 onwards)

Lots of swell potential for next week.

First off, Monday should begin with a small mix of SE swell (from the low off NZ Friday), plus some short range E/SE energy (from the weekend ridge through the Central Tasman) and additionally a small long range E/NE swell originating from tropical developments between New Zealand and Fiji over the coming days (nothing special, just a moderate trade flow so only small size in southern NSW). Local winds will probably be out of the northern quadrant but likely light in strength.

This is expected to be quickly overshadowed by a much better E/SE groundswell arriving during the late afternoon that’s expected top provide great waves through Tuesday. The origins of this swell are interesting: the low off NZ’s South Island on Friday is expected to track slowly northwards on Saturday and merge with the remnants of the trough/small closed low developing east of Byron Bay on Friday, supercharging a fetch exiting western Cook Strait (the body of water between NZ’s North and South Islands). And, the synoptic pattern is expected to remain slow moving for a few days.

This E/SE fetch will be mainly aimed towards points north of Sydney, however we should see excellent surf from this system in Southern NSW on Tuesday, somewhere between 3ft and maybe 5ft at open beaches at times (although inconsistent at times). At this stage there’s no suggestion for any major trend in the wind but it’s early days yet (I’ll update in Friday’s notes). 

Tuesday’s swell is expected to hold into Wednesday, and although an easing trend is likely throughout the day, the fetch off New Zealand’s West Coast is expected to remain anchored in place for a few days meaning we should see good residual swell persisting through Thursday and Friday.

In addition to this, there is also a suggestion that we’ll a stronger cut-off low develop in the Central Tasman Sea around the middle of the week that could generate an additional large SE swell on top of the previous energy for Thursday and Friday. 

It’s way to early to have any confidence in this last weather system, however it certainly fits in with the suggestion I gave in Monday’s notes that next week will "probably head towards some more dynamic developments along the East Coast” as the “atmosphere primes itself for a significant weather event in our eastern swell window”. More on this in Friday’s notes.