South-east Queensland and Northern NSW Surf Forecast by Ben Matson (issued Monday 16th September)

Best Days: Tricky week ahead. Wed has potential with improving winds and a punchy SE swell across the Mid North Coast, but it'll be much smaller in Far Northern NSW and SE Qld won't see much size. Thurs/Fri will see a smaller mix of swells (best in Northern NSW) with OK morning winds. The weekend and early next week has good E'ly swell potential but local winds will remain an issue. 

Recap: A small south swell built across Northern NSW on Saturday around 3ft at south swell magnets, and a bigger south swell pushed 4-5ft+ on Sunday. However, there was a wide range in size across the coast and it was much smaller in SE Qld as expected. A S’ly change on Saturday afternoon was bookended by northerly winds early Saturday and later Sunday. Size throttled back today with mainly 3ft+ leftovers across Northern NSW’s south swell magnets and very small waves in SE Qld. Winds have been out of the north all day as a S’ly change approaches from the south.

Still some leftover S'ly sets in Coffs Harbour this morning

Small leftovers at Sunshine Beach this morning

This week (Sep 17 - 20)

We’ve got an enormously diverse range of swell sources for the coming week and a half.

Probably the trickiest part of this week’s forecast - at least for the next few days - are the local winds. A trough of low pressure is expected to stall off the Mid North Coast tonight, and a low forming along the trough line will strengthen SE winds into Southern NSW on Tuesday, concurrently extending a finger of S’ly winds adjacent the Northern NSW Coast. 

The northern extend of this S’ly fetch is the tricky part, because any locations to its north will experience N’ly winds.

The latest model guidance suggests the axis point between the two will meander between the Gold Coast and Yamba on Tuesday (suggesting the main S’ly fetch will only reach the Tweed Coast), before the low/trough dissipates into Wednesday, allowing for lighter winds. A redeveloping coastal trough will then freshen NE winds everywhere through Thursday and Friday, though strongest in the south and probably not a lot of strength in SE Qld.

Today’s freshening N’ly winds will generate a small NE windswell for exposed north-facing locations in SE Qld, mainly the southern Gold and Tweed Coasts, and some parts of the Northern Rivers. Sets will probably max out around 2ft and it won’t be worth too much effort. Expect poor conditions across the Sunshine Coast under a persistent N’ly breeze but workable options further south with lighter, more variable winds on the Gold Coast, tending moderate to fresh S’ly south from the border. 

Today's southerly change advancing along the Southern NSW coast wasn’t much of a swell generator, but its parent front well to the south was reasonably strong and should kick up a new S’ly swell for Northern NSW's south swell magnets during Tuesday, up into the 3ft+ mark by the afternoon. 

Additionally, we’ll see building SE swells into the afternoon and (more so) Wednesday, from the SE fetch off the bottom flank of the trough. This is best aimed into the Hunter coast so surf size will be smaller as you track north. The Lower Mid North Coast should pick up 5-6ft sets, but we’re probably looking at 3-5ft surf through Coffs Harbour and then 3ft+ up into the Ballina Shire, with only small waves pushing north of the border into SE Qld. 

Wednesday certainly has some potential with winds becoming more variable as the trough eases back but the swell may be quite jumbled. 

After the low weakens into a broad coastal trough, an E/NE infeed will gradually rebuild E’ly swells throughout the end of the week as the local SE swell eases. Thursday will see a mix of energy, biggest south from Coffs with 3-4ft sets (smaller to the north, not much in SE Qld), whilst Friday should see wave heights rebuilding to 2-3ft across most coasts as the E’ly swell fills in. 

Local winds could become a problem during Friday as an approaching front from the south-west tightens the pressure gradient, but most of Thursday and early Friday should be OK with lighter winds. 

It’s also worth mentioning that this week will concurrently experience a series of overlapping long period S’ly groundswells, generated by a succession of incredibly powerful lows below the continent at the moment. 

Peak swell periods could very well top out at 20+ seconds a couple of times in the coming days, but these swells will be smaller in size than the local events, and to be honest, confidence is not high on how much size we’ll see because of their remote, flukey origins. But, it’s possible one of those days (I’m thinking later Thursday or Friday) could occasionally nudge the 4ft mark at south swell magnets south of Byron. 

In any case, the presence of the local swells, alongside generally poor local conditions will render this unusually long period S’ly swell somewhat useless, which is a shame.

This weekend (Sep 21 - 22)

The main synoptic feature for the weekend is a shallow trough that’ll maintain N’ly winds across most coasts this weekend. They’ll be strongest across the Mid North Coast and probably not too much of an issue in SE Qld, but they will be present. A late S’ly change is likely on Sunday afternoon. 

Our local NE airstream later this week will be associated with a broad high pressure system in the eastern Tasman Sea, which will also display a broad easterly fetch off its northern flank.

Whilst most of the swells from this week are likely to have throttled right back, the new E’ly energy building through Friday - sourced from the aforementioned ridge - is modelled to hold in the 2-3ft range at most coasts both days, with a few bigger sets across Far Northern NSW. We may also see some NE windswell across the Mid North Coast on Saturday . 

Let’s take a closer look on Wednesday as local winds will really be the key factor in scoring waves this weekend - and at this stage quite a few coasts look a little dicey.

Next week (September 23 onwards)

The weekend’s fun trade swell should persist in and around the 3ft mark for Monday and Tuesday, a little bigger in northern NSW but a little smaller across parts of the SE Qld and Mid North Coasts. 

Otherwise, beyond this there’s nothing more than the usual frontal progression through our south swell window.

More in Wednesday’s update.