Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Monday 11th September)

Best Days: Tues: early morning at south swell magnets before the swell completely disappears. Thurs: small, building S'ly and SE swells, biggest and best in the a'noon. Fri: decent S'ly swell with offshore winds, easing Sat. Sun: very large S'ly swell. 

Recap: The weekend saw very large southerly swells building from around 5-6ft on Saturday to 8ft on Sunday across Sydney’s south facing beaches, and up to 10ft+ at offshore bombies. Conditions were clean with early offshore winds and afternoon sea breezes. Today we’ve seen a steady drop in size from 4-6ft to 3-4ft at south facing beaches (bigger in the Hunter), with similar surf conditions.

This week (Sep 12th - 15th)

Surf size will ease rapidly through Tuesday and Wednesday. Early Tuesday will have the most size - perhaps some stray 2-3ft sets ay south facing beaches (mainly across the Hunter) but it’ll be very small by the afternoon, and these tiny conditions will persist through Wednesday. 

However conditions should be generally clean with light NW winds and possible afternoon sea breezes. 

Thursday will start off very small, but we have two new swell sources that will kick up size throughout the day. 

The first swell to arrive should be a small inconsistent SE swell from an E’ly infeed into the broad scale low that generated the weekend’s waves. This E’ly fetch was positioned well SE of New Zealand late last week and early into the weekend, and wasn’t particularly large nor strong, so we won’t see much size or consistency - maybe some occasional 2ft sets. 

In any case this swell will likely be overshadowed by an acute south swell originating from W/SW gales exiting eastern Bass Strait late Wednesday and into Thursday morning. The trend will be a little slow on the upwards phase on Thursday (owing to a poorly consolidated fetch in and around Tasmanian waters) however by the late afternoon south facing beaches should be looking at 2-3ft sets (smaller elsewhere, but bigger in the Hunter). Conditions should be generally clean with W’ly winds. 

I’m not confident on the timing of either swell though, so let’s check back on Wednesday as the surface wind outlook offshore from Tasmania should be a little more concrete by then (which will help in pinpointing the timing of the S'ly swell at least).

Friday will then see a peak from this event with set waves somewhere around 3-4ft+ across Sydney’s south facing beaches and up to 4-5ft+ across the Hunter coast. However, the swell direction will be steeply south and thus beaches without good southerly exposure will be considerably smaller. 

Fortunately, conditions will be very clean under a moderate W’ly breeze. So if you have one day to surf this week, make it Friday and aim for your favourite south swell magnet for the most size. 

This weekend (Sep 16th - 17th)

Friday’s south swell will ease through Saturday but conditions will be very clean as a vigorous front and low approaches form the southwest, freshening W’ly winds about the coast. This low will deliver afternoon SW gales about the Far South Coast. 

South facing beaches should hover around the 3ft range early morning but ease back to about 2ft into the afternoon. Expect bigger waves across the Hunter but smaller surf at beaches will less southerly exposure. 

The aforementioned low is expected to intensify rapidly east of Tasmania later Saturday, with surface wind speeds upwards of 50kts across its western flank. This is expected to produce a brief, albeit very large pulse of relatively long period (given the close proximity) S’ly groundswell to Southern NSW on Sunday, that could easily match the size seen this past weekend.

I’m hesitant to commit to a size right now because the low is expected to transition quickly through the swell window, and any small tweaks to its strength, position and/or alignment will dramatically alter the surf size projections. But for now let’s ballpark somewhere in the 6-8ft range for Sunday (south facing beaches) and not be overly surprised if it’s upgraded over the coming days. 

Next week (Sep 18th onwards)

Sunday’s swell is expected to ease rapidly into Monday but the responsible low is forecast to meander about the SE Tasman Sea off the South Island’s West Coast, so we’re looking at moderate levels of S/SE tending SE swell through the middle of next week. More on this in Wednesday’s update.