Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 14th September)

Best Days: Tues: fun combo of S'ly and NE swells with winds tending NW ahead of a late S'ly change. Wed: peaky building S'ly swell with early offshores. Thurs/Fri/Sat: small long period S'ly swell, but with tricky winds (Sat looks the pick at this stage).

Recap: The weekend delivered plenty of fun waves although the sets were very inconsistent. South facing beaches saw occasional 2-3ft sets both days, with early light winds and afternoon sea breezes. A smaller south swell filled in today with sets pushing 2ft at south facing beaches, and freshening northerly winds have whipped up a small low quality NE windswell too.

This week (Sep 15 - 18)

We’ve got a fun peaky swell combo on target for Tuesday.

Right now northerly winds are strengthening across the coast, and the fetch will extend a reasonable distance up the Northern NSW coast overnight. It’s not amazingly strong but it’s sufficient enough to kick up a decent short range swell, with sets likely to reach 2-3ft at most NE facing beaches (smaller in the northern Hunter due to the swell shadow offered by the Hunter Bight). Swell magnets on the South Coast should see a few bigger waves owing to the larger fetch length. 

A southerly change will approach from the south throughout the day, and winds should veer NW at some point in the morning (not 100% on the timing but early-mid morning is a reasonable bet), cleaning up most open beaches throughout the day. There’s also likely to be a small signal of residual S’ly swell in the water originating from the deep low that passed south of Tasmania later Friday and into Saturday. It wasn’t very well aligned for the coast - evident by the small size on offer this morning - but south facing beaches should see some very inconsistent 2ft+ sets. Those open beaches picking up both swells should do pretty well on Tuesday. 

The southerly change is expected into the South Coast during the afternoon and the Sydney region during the evening, but it’s a weird, broad looking pattern with several low pressure centres modelled to be scattered across the southern Tasman Sea. As such, we may not see quite as much local wind on Wednesday as the models are currently indicating, and there’s a pretty good chance that it’ll be SW for a period early morning across many regions too (but not all). South facing beaches should pick up 2-3ft+ of random south swell throughout Wednesday - possibly a little undersized early morning, ahead of an afternoon peak - but the NE swell will be fast diminishing by this time so expect much smaller surf at remaining beaches. 

While all of this is going on, a series of intense lows will have passed through the Southern Ocean, below the Tasman Sea, and they’ll generate some more long range southerly groundswell that’ll fill in underneath the short period energy. This should pad out most of Thursday and Friday with very inconsistent but long lined south swell, somewhere between 2ft and very occasionally 3ft at the swell magnets, but much smaller surf elsewhere due to the swell direction (and long waits for the sets). A marginally bigger round of swell from the same progression is then expected on Saturday.

Otherwise, the models have a weak trough lingering off the North Coast on Thursday before forming a small closed low east of Byron Bay around Friday, and driving a strong ridge up into the Coral Sea. This probably won’t directly influence southern NSW’s swell potential, however we are likely to see an associated southerly flow across the coast that’ll produce a small short range south swell for exposed beaches (and also wreck the quality of the underlying S’ly groundswell too). 

So, make the most of the next few days as the second half of the week looks a little ordinary at this stage. 

This weekend (Sep 19 - 20)

The final front/low combo in the Southern Ocean this week looks like it’ll deliver the biggest waves from this southerly pattern. No major increase in size is expected (in comparison to the previous swells) but it should supply inconsistent 2-3ft+ sets at south facing beaches for Saturday, easing a little into Sunday. 

Winds are modelled to remain from the southern quadrant on Saturday but at this stage they should be light enough to allow for a period of early offshores. Light/variable winds and sea breezes are expected on Sunday as a high builds from the west. 

The only possible sources of swell for the weekend are (1) a small SE swell on Sunday from a small low forming off the SW tip of New Zealand’s South Island on Friday (low/medium confidence right now) and (2) a small late pulse on Sunday from the E/NE, originating from some tropical developments north of New Zealand later this week (medium confidence on the swell, although it's more likely to arrive Monday than late Sunday). I'll have more on the chances of these swells on Wednesday. 

Next week (Sep 21 onwards)

Nothing major standing out in the long term forecast charts, over and above what I just mentioned for the end of the weekend.

However the broader long term synoptic pattern does look rather unstable and this suggests we’ll probably head towards (at some stage within the following week) some more dynamic developments along the East Coast. I realise this is a very broad description, but at the moment there are no synoptic features to align these thoughts with - just a general feeling that the atmosphere is priming itself for a significant weather event in our eastern swell window sometime next week. Let’s see how the charts are faring on Wednesday.