South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Friday 18th August)

Best Days: Sat/Sun: large building S'ly swells, best at outer points in SE Qld on Sunday. Mon: strong combo of easing S'ly swell and a new S/SE swell, with early offshores. Tues: pumping beachies with light ofdshore winds.

Recap: Thursday saw a fun small NE swell across some parts of Northern NSW, though there wasn’t a lot of strength in it. A brief flush of south swell also lit up south swell magnets on the Mid North Coast late in the day. Today’s been very small but clean with offshore winds. I’ve been patiently awaiting an unusual S’ly swell to spread back to the mainland, originating from W/SW gales that developed off the Southern NSW coast in the early hours of the morning. Although there are lots of lines now starting to show across the coast, there’s not much more than an occasional 2ft+ set at exposed beaches (though, with the trend over the last few hours it could be double this by 9pm). Regardless, this is a precursor to a  weekend of large southerly swells.

Late new lines of S'ly swell at Yamba

This weekend (August 19th - 20th)

There’s a lot of southerly activity expected over the coming days. Our surf will originate from three primary sources. 

The first source is the current developing gale to storm force W/SW tending SW fetch off the Southern NSW coast, with S/SW winds developing in its wake as a strong front pushes up along the East Coast. The initial stages of this system are poorly aligned, and the models are subsequently overcalling wave heights due to the high windswell contamination in the mix.

Nevertheless, we will see a steady increase all day Saturday, with mainly W/SW winds ahead of a late S/SW change pushing across the Mid North Coast early-mid afternoon onwards, reaching the Far Northern NSW coast mid-late afternoon. 

Sunday is where we’re we’ll see a second, stronger southerly groundswell kick in, originating from a strong cut-off low that was SW of Tasmania on Wednesday (and has since travelled north-east into the lower Tasman Sea). It will be working on the pre-existing active sea state generated by today’s strong frontal passage, and with fetch around this system expected to be pretty much straight southerly, and the low itself will travelling due north through the Tasman Sea, the resulting forward speed could lend itself to a captured fetch scenario (which exacerbates wave heights compared to similar but stationary systems). 

To give you an idea of where the associated groundswell will be positioned over the weekend - the low generating the peak swell energy will be due east of Tasmania in the early hours of Saturday morning, with the swell trailing some distance behind.

This means that the longer period S’ly groundswell won’t really kick in across our region until Sunday, peaking across northern locations through the afternoon. Accompanying winds will be strong and gusty from the S/SW however we’ll see plenty of size for protected points - they’ll be the only workable locations. 

As for size, expect 4-5ft south facing beaches south of Byron early Saturday, building to 6-8ft by late in the day (smaller at protected locations). However under these conditions you’re only going to be able to surf sheltered points and they’re going to be considerably smaller due to the acute southerly swell direction (at first). 

Across SE Qld, it’s really hard to have a lot of confidence as to whether we’ll see an appreciable size increase on Saturday. All of the swell generating winds responsible for Saturday’s size increase will be be mainly W/SW tending SW so it’s going to have to do a hell of a lot of work to spread back into SE Qld beaches.

Exposed northern ends will be considerably bigger but they’ll be wind affected; outer points should see a size increase throughout the day though through the morning I’m expecting only small surf around 1ft, maybe 2ft from lunchtime onwards if we’re lucky; possibly 2-3ft very late in the day across the Goldy with smaller surf on the Sunny Coast. 

Sunday will be very big across exposed spots. Our in-house surf model is really going way over the top on this event (15ft south facing beaches in Coffs, and 12-15ft at south facing beaches on the Goldy? Yeah, right!) - however we are looking at a powerful swell event reaching 8-10ft+ at exposed south facing beaches south of Byron, and 5-6ft at remaining open beaches in Northern NSW. Fresh S/SW winds will tend SW and ease throughout the day.

SE Qld is where you’ll want to be, though the strong southerly component in the swell direction really concerns me for protected points like Noosa - I reckon they’ll be very small (though winds will be ideal). Outer Gold Coast points should manage 3-5ft sets on Sunday and exposed northern ends will be a wind affected 6ft+ (expect excellent conditions for the points under a fresh S/SW breeze). We will however see slightly smaller surf across the Sunshine Coast. 

Next week (August 21st onwards)

Monday will see a continuation of strong S’ly groundswell though size will initially ease throughout the day. 

However, we have a new source of S/SE for the afternoon that’s just showing up on the models now - our third source of swell in three days - that should arrest the otherwise easing trend. This energy will originate from a secondary low (related to the system generating the weekend’s big surf) but this time located much closer to New Zealand.

Gale force S’ly winds will form around this new low immediately west of the SW tip of New Zealand’s South Island, throughout Saturday afternoon, before it powers north through the Tasman Sea. 

Residual S’ly swell from Sunday should hold out around 6ft+ at south facing beaches (south Byron) on Monday morning, and the afternoon pulse could deliver a similar level of size. Between the two swells we may see a temporary dip in size and energy. 

SE Qld pouter points are looking excellent on Monday morning with light offshore winds and easing 3-4ft sets, though you’ll want to get in early as we’re likely to see a NW tending N’ly flow into the afternoon. A similar afternoon renewal of energy is also possible here (along with a temporary dip through the middle of the day). I’ll try to firm up the specifics over the weekend. 

Looking further ahead and surf size will ease steadily into Tuesday, leaving fun beach break surf across open stretches for the morning session (2-3ft SE Qld, 4-5ft Northern NSW, easing) with light offshore winds. Expect smaller surf into the afternoon. 

A brief front and a possible small Tasman Low may kick up some small southerly swell for the middle of the week though no great size is expected right now. A series of deep Southern Ocean lows further south look poorly aligned for our region so the rest of the week looks a little on the small side, but holding out of the south. 

Anyway, have a great weekend - see you Monday!