Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 27th May)

Best Days: Saturday: solid but inconsistent, and rapidly easing S'ly swell, clean with offshore winds. Sunday: small clean S'ly swell. 

Recap: Wednesday’s very large S’ly swell eased rapidly into Thursday and further into Friday morning, under clean NW tending W’ly winds. A new S’ly swell is building across the region, with 3-4ft sets now showing at south facing beaches. 

Afternoon sets at Bondi

This weekend (Saturday 28th - Sunday 29th):

The fetch responsible for today’s building S’ly swell is quite incredible (see satellite imagery to the right, taken this morning). 

It’s quite tricky to estimate the size potential from this system, as satellite derived winds are actually better aligned than what the models predicted (this increases the swell potential). But overall the broader system is expected to track NE, away from our coast (which reduces the swell potential). 

Also, this system is located almost entirely north of Bass Strait latitudes - for the best southerly swells, we prefer the associated fetch to extend well south of Tasmania. The general idea here is that swells requires a certain distance to become fully developed - if you’re too close to the swell source, you’re at risk of not seeing the maximum potential from the fetch strength. Compounding this is that the fetch is aimed away from the coast, so any “swell spread” we see back into the coast is also reduced below the axis of refraction (which will probably be around Wollongong or thereabouts). 

In short, your size potential will proabably be greater as you head north along the NSW coast (though the Hunter curve compounds this issue for the North Coast; that's another story), and smaller as you head south.

And as we saw on Wednesday, complex systems like this usually throw lots of curveballs our way too. 

Also making Saturday’s forecast tricky is a developing E’ly fetch along the bottom of the Tasman low, which will veer SE in direction as the low tracks NE. This fetch will be well positioned within our swell window at some point (good for swell potential) but will last only a brief time (bad for swell potential). 

See all of the variables at play?

In assessing the current surf conditions, we've already seen a decent increase in new energy start to show later this afternoon but right now there's no major size showing in Sydney, or across our Illawarra surfcams. As such I'm downplaying the size potential from this fetch as I think it hasn't lasted long enough in our swell window to maximise the strengths seen in the surface wind field. 

Right now, the models have strong southerly swell all weekend, but I think they're overcooking the size from Saturday afternoon onwards. It’s quite likely that we’ll see a strong peak in size overnight tonight, but then a steady easing trend all day Saturday, with small surf prevailing through Sunday. 

South facing beaches will see the biggest waves; I’m estimating inconsistent early sets around 4-5ft at reliable south swell magnets at dawn on Saturday (possibly a bigger near 5-6ft+ in the Hunter, but smaller south of Sydney). Overnight - if it were possibly to see through the darkness - south swell magnets could very well push north of 6-8ft, but I just don’t think the peak from this swell is going to last much longer than a few hours, and most of it will be occur under the cover of darkness.

Saturday morning’s early size will trend downwards steadily all day; by lunchtime we’ll probably be around 3ft+ at Sydney’s south facing beaches, and then mid-late afternoon down to 2ft+. All the time, expect smaller surf at beaches with less southerly exposure. Conditions should be clean with moderate to fresh W’ly winds, tending SW in the south during the day and becoming quite gusty late afternoon.

As for Sunday, a redeveloping S/SW flow off the South Coast late Saturday should renew short range S’ly swell across south facing beaches (north of Wollongong) throughout Sunday, pulsing in the 2ft to very occasionally 2-3ft range all day. Bigger waves are also likely in the Northern Hunter region too, but once again - expect smaller surf at beaches with less southerly exposure (and also, locations south of Wollongong). 

Local winds are looking better on Sunday too with light to moderate W/SW winds all day. 

Next week (Monday 30th onward):

The weekend’s local S/SW fetch off the South Coast should maintain small S’ly swell energy for south facing beaches on Monday but it’s expected to ease during the day. 

Otherwise, there are no major sources of swell for next week. A small S’ly fetch in the eastern Tasman Sea (associated with the current Tasman lows later developments across NZ early next week) may deliver some sideband energy for mid-late next week but such a scenario would mainly favour the northern part of the state (owing the to the way the swell will spread back into the East Coast). Don’t pin your hopes on anything for now.

A polar low tracking off the ice shelf on Sunday - that may become absorbed into the broader NZ system early next week - may also generate some side band energy mid-late next week but no great size is likely from this just yet. 

A trough pattern is then expected to develop across the East Coast, but with no great swell potential. Therefore, much of next week will see small residual swells at exposed beaches, and mainly light variable winds.

Towards the end of the week, the coastal trough is expected to consolidate, forming a fresh N/NE fetch and a surface low off the South Coast that could generate a some punchy NE swell throughout Friday and into Saturday. But these systems are quite volatile in where and when they develop (using long range model guidance) and its close proximity to the coast means confidence is low - for example, if you shift the modelled position of the trough 150km west, we won’t see much, if any swell - but there are other synoptic scenarios that could work in our benefit.

In any case it’s looking like more of a typical autumn pattern developing later next week (ironically, in the first few days of winter) and there’s a good chance that we’ll see some strong swell potential over the forthcoming days (Saturday onwards). But it’s way to early to estimate potential size and conditions. 

Have a great weekend, see you Monday.