Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 20th May)

Best Days: Tues/Wed: clean conditions, with a series of long period S'ly groundswells that could potentially show some pretty solid sets late Tues PM. 

Recap: Light winds and small fluctuating southerly swells have provided plenty of waves at south facing beaches over the last few days. Size has been in and around the 2-3ft mark both days, though slightly larger this morning.  

This week (May 21 -24)

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A dominant ridge of high pressure over the Tasman Sea will maintain mainly light variable winds all week. A small trough may throw a brief onshore curveball later Wednesday and early Thursday but at this stage it’s expected to have very little impact on surf conditions (if it does anything at all).

As for surf, the swell charts look devoid of activity but that belies what’s been happening in our acute south swell window over the last few days.

Whilst our weekend and existing southerly swells are/were essentially sideband energy from poorly aligned fronts racing below Tasmania and New Zealand, we’ve got some impressive long period energy - possibly with forerunners up in the 19-20 second range - due to arrive on Tuesday, from an intense low well below Western Australia over the weekend (see below). The swell model isn’t handling this unusual source very well either so is estimating very small wave heights in NSW. 

Although this low pressure system doesn’t look like it’s aimed into our swell window, the above map projection is misrepresenting the true alignment, and in fact it’s reasonably well positioned, albeit a very large distance from the mainland, and also slightly inside the swell shadow offered by Tasmania. 

As such, I think we’ll see a continuation of inconsistent 2-3ft S’ly swell - from today’s source - into Tuesday morning (bigger in the Hunter et al), ahead of some larger sets pulsing every fifteen or twenty minutes, in the 4ft+ range at south facing beaches from about lunchtime onwards, showing best late afternoon. We'll see this swell arrive much earlier along the South Coast though.

Across reliable south swell magnets such as the Hunter region (and offshore bombies) we’re likely to see larger waves pushing 5-6ft+ at times - though they will be very far and few between. Keep in mind that this is an unusual swell source so its impact will result in a wide range of surf conditions, depending on local bathymetry and geography. 

Of course, anywhere not open to the south will be much smaller too.

Surf size will then ease slowly through Wednesday - though early morning could still see a reasonable percentage of Tuesday’s late size increase, ahead of a downward trend throughout the day - and the second half of the week is looking at small residual swell from a series of minor peripheral sources.

Although conditions on Thursday and Friday will be clean with light winds, I’m not expecting much size as the storm track is not lined up very well within our swell window. 

This weekend (May 25 - 26)

A series of cold fronts will clip the southern corner of the state this weekend. However, they’ll remain poorly aligned within our swell window to begin with, so we probably won’t see much of a size increase from this direction until Monday. 

We do have some minor new swell on the way though. A broad though ultimately modest trough will develop in and around the Fijian region this week, and slowly retrograde to the west, building small E/NE swells for our region that’ll gradually increase in size ahead of a peak early next week. 

At this stage exposed beaches should build from 1ft on Saturday to 2ft by late Sunday, and with offshore winds under the frontal influence, conditions should be keen. Don’t expect much size though.

Next week (May 27 onwards)

The E/NE swell mentioned above should peak around Monday, perhaps holding into Tuesday with slow 2-3ft sets at exposed beaches. 

We’ll also see some bigger south swell from a vigorous frontal passage across Tasmania on Sunday. This should light up south facing beaches in the 4-5ft+ range. 

More on this in Wednesday’s notes.