Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 28th September)

Best Days: Sun: lumpy though improving mix of S'ly swells. Next Mon thru' Sun; potential for small long period S'ly swell every day, most size likely Thurs/Fri. Wed thru' Sun: small, but slowly building E/NE swell, peaking over the weekend. 

Recap: A strong S/SE swell built across the coast overnight Wednesday, providing 4-5ft waves to most south facing beaches with rare 6ft+ bombs at offshore bombies, though the sets were pretty inconsistent at times. Winds were light offshore in the morning, and freshened from the N/NE into the afternoon. These winds have persisted through today, and the southerly swell has eased to around 3ft, with a small NE windswell in the mix too. Winds are now veering more NW across southern regions (i.e. Illawarra, South Coast) as a front approaches from the south.

This weekend (Sep 29 - 30)

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A southerly change advancing along the South Coast this afternoon will push into Sydney overnight, but then ease back temporarily early Saturday morning, ahead of a second, stronger surge of southerly winds through the day.

This may create a brief window of lighter SW winds, but it won’t last long (and won’t influence many coasts either, likely just the Northern Beaches). Saturday's renewal of gusty southerlies is expected into the Illawarra mid-morning and Sydney late morning, and the Hunter around lunchtime. 

There won’t be a lot of surf around for the early session Saturday. Today’s south swell is on the way out and the NE windswell will also be easing. Tonight’s S’ly change will generate some short range energy but the bulk size is expected into the afternoon, in the lee of the second southerly surge. And, it’ll be wind affected once it starts to increase - south facing beaches may see occasional 3-4ft sets through the afternoon, but quality will be in short supply, and it'll be much smaller elsewhere.

Fortunately, the front will clear to the north overnight Saturday, leaving Sunday with wobbly but improving southerly swell, easing from 3-4ft to 2-3ft at south facing beaches. The Hunter may pick up a few bigger waves but it’ll be much smaller at locations not open to the south. There’ll also be a small S’ly groundswell in the mix, sourced from poorly aligned frontal activity south of Tasmania today, though no bigger than the pre-existing short range swell.

Winds are expected to be light to moderate on Sunday morning, probably retaining a degree of south in direction (possibly SW in a few locations), becoming variable before lunch and then tending moderate SE after lunch.



So, expect OK waves on Sunday, but it won’t be worth your Instagram account.

Next week (Oct 1 onwards)

The synoptics are really busy for next week, and we have a wide variety of tricky swell sources on the way. In fact, most of the likely energy we’ll see will be generated from distant sources off the usual charts. 

First up: TC Liua is not going to generate any surf for us, nor is the supporting ridge to the south (in the Coral Sea). 

A trough related to tonight’s change will linger in the central / northern Tasman Sea over the weekend, intensifying slightly through Sunday afternoon and Monday. It’s not anything amazing, but will supply some small sideband E’ly swell for us early-mid week. 

This trough will then merge with some new tropical developments south of Fiji (initially a strengthening E’ly fetch from Sunday onwards), broadening a deep surface trough through the north-eastern Tasman Sea through the first half of the week, and forming an impressive E/NE fetch that’ll probably stretch way out into the South Pacific.

The primary fetch is expected to slowly track to the south and will eventually fall inside the swell shadow of New Zealand’s North Island, but at this stage I’ll peg a slow increase in E/NE swell from about Wednesday onwards, building from an inconsistent 2ft up to 3-4ft by the time it reaches a peak around Saturday or Sunday, possibly holding into Monday. Yeah, it’ll be lengthy event, but it'll be slow and infrequent. Not classic but definitely user-friendly. Interesting to note that the models are not picking it up very well right now either.

Elsewhere, and we’ve got an impressive conveyer belt of intense Southern Ocean lows and fronts expected to travel below the continent throughout the forecast period.

If you check the individual forecast data for your local (see below for the Northern Beaches), you’ll notice a lot of long period S/SW groundswell next week; 15 seconds on Monday, 16 seconds on Tuesday, 17 seconds on Wednesday, 18 seconds on Thursday, 19 seconds on Friday, 17 seconds on Saturday and Sunday. Etc.

You’re probably thinking “Huh? Isn’t this the wrong way around - don’t the longer periods arrive first?” And you’d be correct.

What these computer model forecasts are suggesting is overlapping groundswells - each one displaying slightly larger periods, sourced from a storm with stronger core winds. The hardest part is (as always) estimating the size and timing.

I’m never one to sweep a broad brush across the outlook, but in circumstances like this is almost impossible to pin down a blow-by-blow prediction, because southern coasts will feel the new swells earlier than others, and it’s really hard to have confidence in the likely size when there’s two - or maybe three - individual swell trains all hitting the coast concurrently.

Anyway, the main take home points are that because these swells will have been generated by poorly aligned fronts in an extremely remote part of our swell window, there will be (1) long breaks between sets, and (2) large variations in size across the coast.

By and large, most days stand a chance at seeing occasional flurries of 2-3ft sets, but a couple of days in the mix - and I’m honing in towards the second half of the week - could push another foot (or two) on top of this at reliable south swell magnets (I really like the look of Friday at this stage).

But, it’s definitely not an event to pack the car for a road trip - these swells are too fickle and may provide only brief periods of energy. Let’s take another pass on Monday as the models are likely to have moved around by then.

As for winds, the only major fly in the ointment next week is Wednesday when we’ll probably see freshening northerlies. Every other day should have at least a period of light morning winds. 

Have a great (long) weekend - see you Monday!