Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 30th July)

Best Days: Tues - Thurs: small south swell with good winds. Sat: small NE windswell early. Mon: small NE windswell early. Mon onwards: possible E/NE groundswell (low probability at this stage, but worth keeping an eye on). 

Recap: Saturday provided small, inconsistent but rideable south swell around 2ft at south swell magnets, with tiny surf elsewhere. Smaller conditions prevailed into Sunday. Today started off tiny, but this afternoon a new south swell has started to appear though it’s smaller in size and later in timing than expected. Winds have been generally OK for the last few days, mainly offshore though we did see light northerlies from time to time. Fresh W/NW winds developed Sunday afternoon and some regions saw gusty offshores lingering this morning (Bellambi reaching 40kts at 5am).

This week (July 31 - Aug 3)

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Over the weekend I downgraded expectations for today's upcoming south swell, though not because the low/front has lost strength - the swell source being a broad system that crossed the Tasmanian divide overnight, with two fetches expected to contribute swell over the coming 24 hours.

By way of example, check out Hogan Island, which lies immediately E/SE of Wilsons Promontory, upstream from my frequently discussed flukey-south-swell-source-region of Eastern Bass Strait.

Overnight, westerly winds averaged 61kts (121km/hr) or greater from 8:24pm until midnight, with maximum wind gusts reaching 81kts around 11:30pm. 

That's 150km/hr.

It’s worth pointing out that the Beaufort scale’s twelve point rating system has Hurricane strength at the top of the list, which is when average winds are greater than 64kts. As such, Hogan Island experienced Hurricane-strength conditions for two consecutive hours. It’s the equivalent of a Category 5 Tropical Cyclone. 

But, this is a moot point as it relates to Southern NSW’s surf potential, because the main requirement for fetches exiting eastern Bass Strait is that they display at least a whisker of south in their orientation. Alas, winds remained W’ly all night (and all day today), in fact veering W/NW this afternoon. And this has a major bearing on whether we’ll see much energy in the surf zone across Southern NSW.

We have seen some small long period swell glance the coast (Port Botany buoy picking up 18 seconds this afternoon) but to be frank, I’m not particularly confident on how much size we’ll see. Hurricane-force system or not, it simply has to be pointed at least partially towards our coast to be of benefit. South facing beaches now seem to picking up 2ft sets and it’s likely they’ll reach 3ft by close of business but I don't know if we'll see much more size than this - the other issue is that this swell will peak overnight and trend down into Tuesday.

A weaker secondary fetch rounding the Tasmanian corner this morning will contribute some background energy into Tuesday but it too had its orientation tweaked over the weekend by the models.

So in short, I’m not confident on size prospects for Tuesday. I’ll go with inconsistent 2-3ft sets across south facing beaches (bigger in the Hunter, but much smaller elsewhere) and be pleasantly surprised if it’s bigger and more consistent. Expect size to ease throughout the day too. But it’ll be clean with light offshore winds. 

A series of similarly zonal fronts (aligned west-east) will track through the same swell window on Tuesday and Wednesday, offering smaller levels of south swell through Wednesday and Thursday. At this stage 1-2ft+ seems about right for most Sydney south facing beaches through Wednesday and Thursday, though the Hunter always does much better and should see occasional 2-3ft+ sets. Again, conditions should remain generally clean with offshore winds. But don't expect much push in the swell Wed/Thurs as this energy will be glancing the coast at best. 

Friday looks pretty ordinary with freshening N’ly winds and building N/NE windswells. So, make the most of the next few days of flukey, intermittent southerly swell.

This weekend (Aug 4 - 5)

Friday’s freshening N’ly breeze should generate some local windswell though a front is expected to cross the coast around midnight, cleaning up conditions and shutting off the swell source. As such, we can expect small, average and easing N/NE windswell on Saturday morning, with early 2ft+ sets at reliable swell magnets easing to 1ft+ throughout the day. 

Very little surf is expected on Sunday, as the front crossing the coast isn’t expected to have a parent system to the south, so we won’t see much, if any southerly component in the trailing fetch. Early light winds will freshen from the NE in the afternoon.

Next week (Aug 6 onwards)

Sunday’s freshening N’ly breeze should generate another small windswell for Monday though no great size is expected.

Elsewhere, and the models are showing some interesting developments north of New Zealand later this week. A broad but initially weak trough will slowly gather strength and by the weekend could very well display some incredible winds around its eastern and southern flanks (see chart below).

However, at this stage model guidance suggests it’ll reside mainly inside the swell shadow of New Zealand’s North Island - resulting in a large E’ly groundswell for SE Qld and Northern NSW, but with much smaller surf in Southern NSW. 

That being said, a small northward shift in the projected location of this low could easily swing things in our favour, so I’l keep a close eye on things over the coming days. 

See you Wednesday!