South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Monday 29th August)

Best Days: Wed: shame about the northerlies as we're expecting a long period S'ly swell to build across Northern NSW during the day. Thurs: small combo of easing swells (mainly S'ly) and NW winds in Northern NSW. Not much in SE Qld. Sat: late afternoon window of strong N'ly swell at exposed beaches and a W'ly change. Aim for a late session. Sun: clean mix of easing N'ly tending E/NE swell and building S'ly swell (the latter only in Northern NSW). 

Recap: Easing swells resulted in very small surf across SE Qld all weekend, but Northern NSW picked up a small south swell on Saturday and conditions were workable at a few spots in the morning before gusty S/SW winds took over most regions. Sunday saw smaller surf with better conditions - early light offshores and moderate afternoon sea breezes. A new SE swell from the trough/low in the Central/Northern Tasman Sea arrived a little later than expected, not really showing until this morning across Northern NSW where it blended with a pulse of long range S’ly groundswell (Crowdy Head picking up 13.8 seconds around 9am). This SE swell also provided small clean surf across exposed Gold and Sunshine Coast beaches in the 2ft range. 

This week (Tuesday 30th - Friday 2nd)

First up - the trades developing across the Coral Sea are really too far north to benefit most regions with any notable size. A small front riding around the eastern periphery of the Tasman Sea will merge with the tail end of the trades later Tuesday, and may provide a small reinforcing pulse later this week across SE Qld but no major size is expected from it.

Otherwise, we’ve got a lot of activity in our south swell window. However, as discussed on Friday, confidence is low for this event. 

The reason being is that the low pressure system responsible for the swell is (1) poorly aligned within our swell window, (2) a very large distance from the mainland, and (3) travelling quickly perpendicular to the great circle paths.

So, despite a broad fetch of 50kt winds at the low’s core (most of which is aimed into the South Pacific rather than the Tasman Sea), the surf we see across Northern NSW will be sideband energy and is likely to be very selective in where it focuses the biggest and best waves (nothing of any substance is expected in SE Qld).

Besides low confidence in the eventual wave heights, it’s also hard to be confident in just when this swell might arrive across the coast. Swells that travel large distances from their source have large(r) error margins, and leading edges originating from embedded fetches within active sea states are often more difficult to pinpoint because the presences of pre-existing swells can make it more difficult to detect the precise phase of the swell once it makes landfall.

Prior to the arrival of this new south swell, Tuesday will most likely see a slight drop in size and energy from today, with light winds and sea breezes. So hit up the swell magnets (preferably south of the border) early morning if you’re keen for a paddle.

The aforementioned trade swell should keep exposed beaches across the Sunshine Coast rideable with sets in the 1-2ft range, but it’ll be smaller south of here. 

Later Tuesday, the lower Mid North Coast may see the leading edge of the first of two long period S’ly groundswells, originating from the polar low progression. However, Wednesday morning is a safer bet to see any appreciable size. 

Wednesday is D-Day for this southerly groundswell. Although confidence is low on the size and trend, if anything we’ll see a morning peak across the Mid North Coast and an afternoon peak across the Far North Coast (read: locations north of Coffs may be undersized early morning).

However, freshening northerly winds are going to ruin the party across Northern NSW - they may only be light at first and more NW in direction, but by mid-morning they’ll gather strength before freshening into the afternoon. The Mid North Coast in particular could see rather gusty conditions later in the day. 

As for size, south swell magnets south of Byron Bay should peak somewhere between 3ft and maybe 5ft though I’m expecting extremely long breaks between the sets. Late afternoon should also see a small N’ly windswell developing across southern regions. 

South swell magnets north of the border may pick up a few stray 2-3ft sets but for the most part I’m expecting this southerly swell to bypass most of the Gold and Sunshine Coast. Winds will be a little lighter here so some exposed northern corners could do OK with the mix of long range south swell and minor trade swell.

Thursday looks better on the surface as an unstable troughy pattern develops across much of eastern NSW, leading to lighter NW winds however there’s likely to be some residual scarring on the surface from Wednesday’s winds.

The south swell will be well and truly on the way out by this time, though exposed south swell magnets in Far Northern NSW may pick up some stray 2-3ft+ sets before it loses more size (probably half) during the day. Small N’ly wind waves should be present early morning across north-facing beaches across the Mid North Coast though no quality is expected. 

Later Thursday we’re looking at redeveloping N/NE winds across many areas as an inland trough develops across eastern NSW. This is expected to result in a pretty horrid day of waves on Friday with gusty cross-shore winds and low quality windswell. If there’s a positive, it’s that surf size will be on the build throughout the day.

This weekend (Saturday 3rd - Sunday 4th)

The synoptics look rather active for the weekend. 

A deep inland trough is expected to slide south-east, reforming over the southern Tasman Sea as a large Tasman low pressure system at some point on Saturday, and we’re looking at two swells from it - initially a short range N’ly swell on Saturday as the trough draws near the coast, and then a (potentially) solid S’ly swell on Sunday as the low pushes east into the Tasman Sea.

For our region, the northerly windswell looks like it will be the best swell source.

A strengthening fetch in our immediate swell window through Friday and overnight is expected to reach gale force strength or higher by Saturday morning, before winds abruptly swing W’ly at some point as the trough crosses the coast - at this stage scheduled for the afternoon.

Under these scenarios, there’s a crucial period shortly after the winds swing W’ly; the N’ly fetch is usually still active, so it’s pumping out energy but conditions clean up rapidly, offering a window of 2-5 hours of quality beach breaks. And as our coastline is well conditioned to peaky short range swells running almost parallel to the coast, there's a very good chance for some great waves spread out across the long stretches of beachies. 

Of course, this is all dependent on the timing. If the W’ly change pushes through at 5:30pm, the swell will largely go to waste as the best conditions will occur overnight. Right now it looks like we’ll see the change around lunchtime or early afternoon so I'm hopful for a mid-late afternoon session (I’ll firm up the specifics on Wednesday). 

As for size - this fetch looks pretty beefy so I wouldn’t be surprised if NE swell magnets across SE Qld (mainly southern Gold Coast) and Far Northern NSW saw a peak somewhere in the 3-5ft range, with slightly smaller surf at remaining locations. Let’s wait and see how the mid-week model runs are looking.

As for Sunday, we’ll be on the backside of the short range N’ly swell event though a E/NE indeed should keep exposed beaches humming with smaller cleaner waves. More importantly, the developing low in the Southern Tasman Sea is expected to generate a strong return south swell that could light up south facing beaches with solid south swell during the day. And winds are likely to remain offshore W’ly all day. 

However, it’s too early to pin down the specifics, so let’s see how things are looking on Wednesday.

Next week (Monday 5th onwards)

Sunday’s Tasman low will be the dominant weather system for a day or two, so early next week looks like it’ll be influenced by leftover south. There are no other systems on the long range charts at the moment, so we’ll be able to hone in on the specifics of this event over the coming days.