Sydney Hunter Illawarra Surf Forecast by Ben Matson (issued Wednesday 30th June)

Forecast Summary (tl;dr)

• Easing S/SE groundswell Thurs, clean with light winds
• Building E/NE swells from Friday into the weekend with generally good winds
• Sizeable NE swell peaking Mon with winds tending SW
• Plenty of strong though easing E/NE swell Tues thru' next weekend (!)

Recap

Tuesday’s south swell provided 3-4ft waves across most south facing beaches, bigger across the Hunter to 4-6ft, with generally OK conditions as winds became light and variable (though easterlies did come up across the Hunter through the middle of the day). A drop in size to 2-3ft at south facing beaches this morning preceded the mid-late afternoon arrival of long period S/SE groundswell, from a polar low that was south of New Zealand on Monday. Peak swell periods have reached 17.5 seconds at Sydney (2:30pm arrival) though Tp values of 19 seconds were recorded at Eden around 10am. Surf size has already built to 4ft across most south facing beaches (smaller elsewhere) though there are reports of some bigger waves at regional swell magnets.  The swell trend is still upwards too.

New S/SE groundswell lines at Manly late Wednesday afternoon

This week (July 1 - 2)

The new S/SE groundswell will peak overnight and ease through Thursday. As such, the early session will offer the most size: perhaps 3-5ft at beaches with excellent southerly exposure, but smaller elsewhere and likely to trend steadily down throughout the day. Expect very long breaks between the sets. 

We’ll then see much smaller S/SE swell on FRiday, but a growing blend of E/NE trade swell (from a broad ridge across the Tasman Sea) and more noticeably, a short range NE swell from a developing fetch just off the coast. Early morning may be a little undersized in the 2-3ft range but the afternoon should start to push 3-4ft. 

As for surface conditions, a weak coastal trough will maintain generally light winds, from the N/NW if anything so conditions should be nice and clean. There’s a risk for a brief NE incursion around Thursday afternoon - mainly across the Hunter - but I don’t think it’ll amount to much. 

This weekend (July 3 - 4)

The weekend looks a smidge better than Monday’s notes indicated, which was already a very positive outlook anyway. 

We’ve got a broad spread of E/NE thru’ NE swell thanks to a stubborn high pressure system across NZ, butting up against a pre-frontal trough of low pressure across the Southern NSW coast, which should create locally light variable winds, probably offshore.

The stationary nature of the swell source should increase surf size and consistency (compared to a transient fetch of similar strength). And with a minor strengthening in the models over the last few days, I’m slightly increasing projected surf size from 3-5ft at NE facing beaches on Saturday (smaller at south facing beaches, and across the northern Hunter) up to 4-6ft into Sunday afternoon, ahead of a peak in size on Monday. 

I’ll fine tune things in more detail on Friday, but right now the weekend’s looking pretty tasty.

Next week (July 5 onwards)

Monday’s peak in E/NE swell should push 5-6ft+ at most open beaches, sourced from a peak in wind strengths across in the central/western Tasman Sea late Sunday (see below). I wouldn't be surprised if there's a few locations holding 6-8ft for a few hours, this will depend on how quickly the peak wind strengths hold in the swell window. But, the surf should be strong and consistent at most coasts.

A developing low along the trough line will freshen early W/SW then SW winds through the day, a few locations may see a brief period of S/SW winds but it should remain favourable for the most part without too much strength. Another big tick.

Although we’ll see surf size trend down from Tuesday onwards, the ridge across the Northern Tasman Sea - stretching out into the South Pacific - will remain active until next Wednesday or Thursday. That’s the same fetch already in place, which means it’ll remain a swell generating machine for more than a week. And thus, will pump out swell into next weekend (albeit smaller in size). 

Ball park size range is 4-6ft early Tuesday, then down from 3-5ft to 3-4ft on Wednesday and then holding 2-3ft from Thursday thru’ Saturday.  

At the same time, several small low pressure centres embedded at the bottom of the trough line should kick up sporadic S’ly swells in the 3ft+ range for Tues/Wed.

Oh, and there’s a couple of small long range S’ly swells expected in the mix all week (from migrating polar lows below the continent) but they probably won’t be noticeable thanks to the pre-existing energy. 

Conditions look pretty good all week with a lack of synoptic wind, though there’s a risk for brief N’ly flows around Thursday. 

All in all, a pretty fantastic run of surf coming up for Southern NSW.

See you Friday!