Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 13th July)

Best Days: Tues/Wed/Thurs: fun pulsey south swell with good winds. Sun: building S'ly groundswell with light winds. 

Recap: Tiny leftover S’ly swell and a meagre NE windswell on Saturday, trending near-flat on Sunday and early this morning, with gusty offshore winds for most of the time. A new southerly swell is starting to build across the coast in response to a developing Tasman Low off the South Coast (see image below, Bondi at 4pm). 

This week (July 14 - 17)

Looks like last week’s expectations for this week are holding steady for Southern NSW.

The low developing of the South Coast will retain a strong SW component in the wind field within our swell window, thanks to a broad upper low and an approaching secondary surface low to the SW of Tasmania. As such, despite winds being very strong across the coastal margin, the poor alignment of these winds (relative to our swell window) will cap wave heights compared to a straight southerly or south-easterly fetch.

The building trend we’re seeing now will probably reach a peak overnight and then ease throughout Tuesday. Due to the complex fetch structure around this multi-centered low pressure system, it’s hard to pin down the exact swell phases over the next few days. Additionally, there’ll be a significant range in wave heights across the coast, compared to most south swells, so many beaches will miss out on waves. 

The swell energy expected overnight and early Tuesday will have been generated by SW gales extending NE from eastern Bass Strait. But another front approaching Tasmania today will provide a secondary source as it pushes east of Tasmania tonight.

As such, I think we’ll probably see a downwards trend throughout Tuesday ahead of the secondary pulse arriving across the South Coast into the afternoon, reaching Sydney late in the day and persisting through Wednesday morning. This secondary pulse won’t provide any more size but should arrest the otherwise easing trend.

As for size, Sydney’s exposed south facing beaches should see see infrequent 3-4ft+ at times early Tuesday ahead of the abating trend (down to 2-3ft by lunchtime). Much smaller waves are expected at beaches without favourable southerly exposure, but we should see larger sets across the Hunter region near 4-5ft+ at times on Tuesday (probably just in the morning). Just bear in mind that the bigger sets will be quite inconsistent at times, owing to the off-angle fetch alignment. 

The secondary pulse due later Tuesday and into Wednesday should provide 3-4ft waves across south facing beaches, and up to 4-5ft across the Hunter. Again, it’ll be much smaller at beaches with less southerly exposure.

As for local winds, we’re looking at excellent conditions as the low drops to the south, reducing the pressure gradient across most coasts. This should result in light to moderate W’ly winds on Tuesday trending light NW on Wednesday.

On Tuesday, another low pressure centre is expected to develop SW of New Zealand’s South Island, forming another southerly fetch aimed into our swell window.

Whilst the long travel distance and weaker strength will impact potential size, it’s still looking good for another burst of S/SE swell through Thursday, probably in the 3ft+ range at south facing beaches, and 3-5ft across the Hunter (smaller at beaches not open to the south). Our surf model isn’t picking this system up very well just yet so we’ll have to wait and see how it performs over the coming days. 

Regardless, Thursday looks good conditions-wise north of Wollongong with freshening W/SW winds, but it’ll be tricky to the south with a new low pressure system expected to form close to the coast during the day, probably driving onshore winds to many areas. 

In fact, this next system looks like a possible contender for an East Coast Low - and if current model guidance pans out we’ll be looking at a wet and windy day of waves on Friday with a large local SE windswell across the region. Right now it’s too early to pin down any specifics so I’ll take a closer look at this in Wednesday’s notes.

This weekend (July 18 - 19)

Right now, the broader surf trend for the weekend hinges somewhat on the developing low off the coast later Thursday and Friday. 

Whilst the models are in general agreement that this synoptic event will occur, we’re still not sure how much size it’ll generate Friday, and therefore how much size will be leftover Saturday as it departs our region.

But - just to throw in a curveball - we’re also looking at a steady building trend in new long range southerly groundswell over the weekend too, culminating in a peak around Monday. A series of intense polar lows (three of ‘em) are expected to push off the ice shelf into our far southern swell window from Thursday through Sunday; the first new swell will only be small but should arrive Saturday ahead of a bigger round of energy on Sunday.

As such, the overall trend is for an easing combo of southerly and south-east swell on Saturday (let’s ballpark in the 4-5ft range early morning, smaller later), with easing SE winds, possibly a few pockets of light SW winds. 

Sunday looks to be the pick of the weekend with the building southerly groundswell replacing the fading SE windswell, and winds tending light and variable as a broad high pressure ridge envelops the region. At this stage, south facing beaches could be seeing anywhere between 3ft and occasionally 5ft of quality long period energy, with bigger waves at swell magnets and in the Hunter (note: the upper end of this size range will be contingent on core wind speeds reaching 45-50kts and peak swell periods touching 16-18 seconds). Let’s see how Wednesday’s model runs are looking. 

Next week (July 19 onwards)

If the current model runs hold true, next Monday will see the final day in this series of building south swells, with great waves likely at many exposed beaches. After this there’s nothing significant on the radar except a continuation of poor lows through the Southern Ocean that should maintain small to moderate south swell through the middle part of next week. More on this on Wednesday.