Sydney Hunter Illawarra Surf Forecast by Ben Matson (issued Monday 28th June)

Forecast Summary (tl;dr)

• Peak in S'ly swell Tuesday with generally light winds
• A better S/SE groundswell for late Wed/Thurs, though may peak overnight, clean with light winds
• Building E/NE swells over the weekend with generally good winds
• Strong NE swell peaking Mon with a S'ly airstream

Recap

Intermittent southerly swells have graced the Southern NSW coast over the last three days, generally pulsing 2-3ft across Sydney’s south facing beaches but bigger across the Hunter (reports of occ 4-5ft sets on Sunday). Conditions were clean both days of the weekend with light offshore winds, though moderate southerlies have encroached many - but not all! - coasts this morning (i.e. Northern Beaches didn’t swing until 3pm, though the Central Coast swung around 9am and Newcastle swung around 1:30pm).

This week (June 29 - July 2)

We’ve still got a few more southerly swells on the way.

The first is building at the moment, and will reach a peak on Tuesday morning, somewhere in the 3-4ft range at most south facing beaches but somewhere between 4ft to occasionally 6ft across the Hunter.

This swell was generated by a strong front that pushed south of Tasmania over the weekend, but has since cleared to the Southern Ocean below New Zealand and is undergoing a secondary polar development that’ll deliver a better S/SE swell for late Wednesday and early Thursday.

As for Tuesday’s conditions, we’ll be under a weak ridge of high pressure so there’ll be light onshore in some regions but most spots should see periods of light variable winds, particularly in the morning. Main region at risk on Tuesday is the Hunter where the SE flow may linger a little longer than elsewhere.

Conditions for the rest of the week look pretty good with mainly light and variable winds. Brief N’ly incursions are possible as a high muscles up in the Tasman Sea, but they’ll be short lived, and not terribly strong either (Thurs/Fri the most likely days to be influenced).

As mentioned above, the next south swell is being generated by a secondary intensification of the same low for the current building S’ly swell - but this time well south, even S/SE of New Zealand (see below).

As a result, the swell direction will be S/SE across Southern NSW, and the larger swell periods associated with this energy (15-16 seconds) should boost what’ll otherwise shows as relatively low Hsig values across the regional wave buoys. 

Early Wednesday will see rapidly easing S’ly swells from Tuesday (early 2-3ft sets at south facing beaches, smaller later, though bigger on the Hunter) ahead of the new energy that’s due into the South Coast around lunchtime and they Sydney mid-late afternoon.

Unfortunately, at this time of the year it’s getting pretty close to dark by this time, so there is certainly a chance it may not arrive until it’s too late - resulting in an overnight peak in size, before trending down through Thursday.

How big? Most open south facing beaches should pick up 3-5ft sets, but the larger swell periods could nudge this a little higher at some of the regional swell magnets however beaches not open to the south will be much smaller. 

Also, remember that the timing of the peak of this swell will be overnight. Without wanting to hedge bets too much, there’s always a chance that the best part of this swell will fall under the cover of darkness (South Coast would have been the most likely coast to see the bulk size, late Wednesday - though Covid-19 restrictions will reduce options for those who’d ordinarily travel for such swells).

Easing surf size will then continue into Friday, though we’ll see a building E/NE swell thanks to a strengthening mid-week ridge across the northern Tasman Sea. It appears that a coastal trough should keep these freshening winds from encroaching the coastal margin (in general), which should maintain favourable conditions, as wave heights build from 2ft early to 3-4ft by the afternoon.

This weekend (July 3 - 4)

I really like the look of this developing ridge/trough combo. It should allow for light winds for much of the weekend, as surf size continues to increase from 3-4ft Saturday, to 3-5ft later Sunday. With direction out of the E/NE thru’ NE, most coasts should light up with really good quality waves. 

The fetch across the northern Tasman will be slow moving, which will help to boost size (compared to a transient fetch of comparable strength) and its sustained nature will probably increase the consistency of set waves considerably too (see below).

Let’s fine tune the details on Wednesday.

Next week (July 5 onwards)

A peak in the E/NE swell is due on Monday, probably somewhere in the 4-5ft range, maybe 4-6ft at some of the more reliable swell magnets.

However by this time the trough will have pushed a little further off the Southern NSW coast, freshening S’ly winds across the region. Still, they shouldn’t be too strong to conditions should be OK at many beaches (mainly southern ends).

Note: this size outlook is based on the model guidance holding firm with the position and orientation of the fetch (as per above) however a slight nudge to the east would result in a downgrade. So, we'll need to monitor things closely over the coming days.

The next round of swell looks to be a mid-week S’ly pulse though no major size is expected. 

More details on Wednesday. See you then!