Sydney Hunter Illawarra Surf Forecast by Ben Matson (issued Wednesday 21st July)

Forecast Summary (tl;dr)

• Steadily easing S'ly swell Thurs with light offshore winds becoming variable by lunch, late N'ly possible
• Small reinforcing S'ly swell Fri with moderate NW winds, best suited to Hunter
• Small, low confidence S'ly swell Sat with fresh W/NW winds, best suited to Hunter
• Tiny everywhere Sunday with gusty offshore winds
• Small surf and breezey conditions for much of next week

Recap

Small clean surf eased from 2ft at south facing beaches early Tuesday, becoming smaller during the day. Today has seen strong W/SW tending SW then S/SW winds, and initially small surf building rapidly during the day, reaching 6-8ft at south facing beaches into the afternoon. Much smaller surf was reported elsewhere due to the southerly direction.

Mid-arvo S'ly sets across the Manly stretch

This week (July 20 - 23)

So, today’s large windy south swell is at its peak, and will trend down steadily through Thursday.

Fortunately, the front responsible has cleared to the north-east so we’ll see winds ease rapidly overnight and swing light W’ly. Some exposed spots - perhaps just the Hunter region - may see a lingering moderate S/SW flow just before dawn but by early-mid morning we should be under light offshore breezes (trending variable by lunchtime) and steadily improving surf conditions. A late N’ly breeze is likely from mid-afternoon onwards.

As for size, expect the biggest waves at dawn, holding 4-6ft at south facing beaches, slightly bigger across the Hunter but much smaller elsewhere. Size will abate to 3-4ft by the afternoon at south facing beaches.

On Friday, we’ll see the current S’ly swell ease even further, but a small long range S’ly swell from a poorly aligned front below Tasmania today may kick up inconsistent 3ft sets at south facing beaches, mainly the Hunter region. Elsewhere it’ll be a lot smaller, and along break between sets too.

Overnight N’ly winds on Thursday should veer NW into Friday morning as another front slips south of Tasmania, so most open beaches should remain clean - best at protected northern corners - though there’s a risk the wind may swing back to the north into the afternoon. 

This weekend (July 24 - 25)

Not a lot of change to the weekend outlook.

Model guidance suggests tiny surf with freshening W/NW winds Saturday, tending strong to gale force W’ly on Sunday as another series of powerful fronts push across the south-eastern corner of the country.

By and large, this is probably what will eventuate across most coasts. In the wake of the current front, the Southern Ocean storm track is aligning in a zonal pattern - west to east, unfavourable for the Australian East Coast - and this is pushing all of the swell past New Zealand, out into the South Pacific.

However, an intense trailing polar low behind the system responsible for Friday’s small S'ly swell - well south of Tasmania early Thursday - may just light up our far swell window enough to generate a small flush of southerly swell for Saturday. Its slightly more southern position, aided by an active pre-existing sea state, also tips the balance slightly in favour of there being some waves generated. 

As such, I’m going to maintain my outlook for inconsistent 2-3ft sets at south facing beaches on Saturday, but they’ll probably be mainly found across the Hunter region, with smaller surf south from here, and tiny to flat conditions at beaches not open to the south.

Sunday will see this swell almost disappear.

The only energy on the cards for this weekend is a minor distant E/NE swell from a blocking high positioned near Tahiti last weekend, which may provide inconsistent 1.5ft sets every so often. But it's not worth worrying about.

Next week (July 26 onwards)

The outlook for this weekend’s strong Long Wave Trough progression across the country and into the Tasman Sea has been titled slightly away from our primary swell window early next week, so right now we’ve got a small pulse of south swell on the cards for Monday but not a lot for the following days.

The rest of the week looks quite similar with more vigorous fronts crossing the eastern states, most of which look like they’ll steer around the favourable parts of our swell window. Argh.

So, despite a dynamic synoptic chart that would otherwise suggest plenty of size, we’re potentially staring down the barrel of small windy options for quite a few days.

I’ll take a closer look on Friday.