Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Friday 21st October)

Best Days: Sat: fun NE swell with good winds early morning. Sun: small waves at southern ends into the afternoon. Mon/Tues: large S/SE swell building across the coast, light to moderate onshores through Mon PM but super clean Tues AM with light NW winds. Wed: smaller but clean leftovers. 

Recap: Thursday’s mid-range S’ly swell and this morning’s NE windswell pushed a little bigger than expected though conditions remained below par with mainly moderate onshore breezes. We’ve seen a drop in size this afternoon with tiny surf now prevalent across the Sydney coast, which is somewhat against model forecasts for a slight increase. I wouldn’t be surprised if it rebuilds again late afternoon.

This weekend (Oct 22nd - Oct 23rd)

Despite the current easing trend in NE windswell, the fetch off the coast is expected to remain at strength overnight and into Saturday morning. This is slightly stronger than Wednesday’s models were suggesting, and given this morning’s marginally higher-than-predicted surf size, we should see some fun waves across the region as an approaching S’ly change results in a brief window of clean conditions.

The expected wind regime for Sydney is likely to swing from an early NW breeze (around dawn) to a light W’ly through early-mid morning, then moderate to fresh S/SW by mid-late morning, before fresh to strong S’ly winds kick in after lunch. 

This same wind trend will develop across other regions though the South Coast will see it unfold earlier (fresh S’ly winds by mid-morning, fresh to strong on the South Coast around dawn) but the Hunter may see the offshores persist a little longer than Sydney.

In any case it all points to the morning offering the best waves. NE facing beaches should manage 2-3ft+ sets though it’ll be much smaller at south facing beaches, which includes broad regions like Cronulla. The Northern Hunter will also see smaller surf owing to the swell shadow of the Hunter curve.

The South and Far South Coasts may see slightly bigger surf but I’m worried that the earlier arrival of the southerly change (into the Far South Coast just after midnight) will shut off the swell supply before the sun comes up. So the downwards trend will kick in earlier here.

Building short range southerly swells in the lee of the change will increase wave heights at south facing beaches into Saturday afternoon, though no great size is expected initially - 2-3ft south facing beaches, perhaps a very late extra kick - due to the head of the fetch being poorly consolidated. The South Coast will be closer to a stronger developing fetch though and could see some chunky sets through the afternoon. Winds will be pretty gusty out of the south though.

Sunday is where the size will really start to build, thanks to a developing multi-centered Tasman low that's going to generate great waves early next week.

Several fronts are expected to wrap around the primary low; the first on Saturday (mentioned above) but the next one is due into the South Coast overnight, reaching Sydney around dawn on Sunday with 30kt+ S/SW tending S’ly winds across the coastal margin. There is a low chance for a brief period of SW winds right at dawn but this will probably be contained to just a few locations like the Northern Beaches, and possibly the Hunter coast (though SW winds aren’t great here).

These winds will kick up a solid short range S’ly swell throughout the day - possibly a little undersize early morning - but likely to reach 4-6ft at south facing beaches into the afternoon. Southerly gales will write off exposed spots but protected locations should have smaller cleaner waves. 

Next week (Oct 24th onwards)

While Sunday’s windy waves are building across Southern NSW, the parent Tasman Low will be intensifying in the mid-southern Tasman Sea, halfway between Tasmania and the southern end of New Zealand’s South Island. This is slightly more south and west than Wednesday’s model guidance indicated, which means the resulting swell direction will have a little more south in it (i.e. S/SE). And pushing that theory a little further, it means protected spots will be slightly smaller than a similar swell event with more east in its direction.

The models have also sped up the development of this weather system, so we’re now looking at an earlier building trend throughout the day on Monday - arriving across the South Coast mid-morning, and then the Sydney region through the afternoon - ahead of an overnight peak, possibly holding into Tuesday morning but with a definite easing trend during the day. 

Monday should see early light SW winds (possibly W/SW in a few regions) but there’ll be some leftover lumpiness from Sunday night’s breezes. Surf size will likely ease back a little from Sunday afternoon but not much; south facing beaches should see see solid 4-5ft sets and it’ll only get bigger as the day progresses (the South Coast probably won’t see a drop in size at all, as the two swells overlap). 

By Monday afternoon we should be looking at 6-8ft surf across exposed south facing beaches, and winds are likely to be light to moderate SE, so probably not causing too many problems. Protected southern ends will be smaller, more manageable, and a little cleaner.

Note: this trend is slightly at odds with our surf forecast model, which I don't think is seperating the two swells very well (older easing mid-range, plus new building groundswell). I'll keep a close eye on model developments over the weekend but I feel pretty confident that Monday afternoon will see bigger surf than the morning session once the new groundswell starts to show properly. 

Tuesday morning is still the pick of the forecast period. Wave heights will ease slowly during the day but we should see light NW breezes in the morning and very clean conditions.

Surf size will dry up from the south, so expect the smaller end of the forecast spectrum across the South Coast and the upper end across the Hunter coast, anywhere from 5-6ft down south to 6-8ft across the Hunter (with the Sydney/Gong region falling somewhere between). If you’re up for an offshore bombie, surf size will be even bigger at focused reefs. But make the most of the early morning size as it'll become smaller during the day. And again, expect smaller surf at beaches not completely open to the south.

Following Tuesday’s easing trend, wave heights will then fall off more rapidly into Wednesday leading to small residual conditions by Wednesday afternoon and early Thursday as winds veer back to the north.

Looking further ahead, and a weak southerly change alongside an upper trough on Thursday is expected to trigger a new surface low close to the Southern NSW coast sometime Thursday afternoon. This is expected to strengthen southerly gales about all regions into Friday, with a possible deepening Tasman Low bringing more strong southerly swells next weekend. 

More on that in Monday’s notes.. ’till then have a great weekend!