Sydney, Hunter and Illawarra Surf Forecast by Ben Matson (issued Wednesday 15th April)

Best Days: Thurs: smaller early, then an a'noon kick in new SE groundswell, peaking o'night, then easing Fri. Clean with good winds. Sat/Sun: steadily building S'ly swells all weekend - potentially sizeable at south swell magnets on Sun - easing Mon. Good winds Sat but looking tricky Sun/Mon with a possible closed low off the coast.

Recap: The expected new S/SE swell came in a little later than expected (Tuesday arvo) and didn’t quite reach the predicted size, but we’ve still seen some really good waves across the coast. Size has hovered around the 4ft mark both yesterday and today at south facing beaches (bigger across the Hunter) with a few bigger sets today as the swell period lengthened a little more. Conditions have been cleanest in the mornings ahead of afternoon sea breezes. 

Wednesday morning bowls at Shark Island 

This week (Apr 16 - 17)

Thursday’s looking nice and clean with light to moderate NW winds. Today’s S/SE swell will ease back in size but south facing beaches should still manage the odd 2-3ft set early, before size fades a little more through the day. 

By about lunchtime, I’m expecting the regional wave buoys to have picked up the leading edge (15+ seconds) of a new SE swell generated by an intense low that formed S/SE of New Zealand on Monday - in actual fact, a merger between the low that generated our current swell, and a new polar low. 

This system intensified rapidly with surface winds reaching 40-45kts+, but it was located in a remote, flukey part of our swell window and only displayed a favourable alignment for a short period of time. As such, confidence is not especially high for this swell, and how much of the coast it’ll properly influence. 

At this stage I’m still expecting most exposed coasts to pick up 3-4ft+ sets from this source - very inconsistent at times - though the swell periods could result in exaggerated wave heights at some of the more reliable swell magnets, perhaps up near 5-6ft range. Though, I certainly couldn’t would bank on this occurring - I’m just flagging it as an outside possibility, so that there’s no great surprise in the event it does occur.

We’ll see this swell peak later Thursday and overnight into early Friday before falling away through the day. Friday’s winds look pretty good too, mainly light and variable. 

This weekend (Apr 18 - 19)

We’ve got another amplifying node of the Long Wave Trough on the way. It’ll approach Tasmania later Thursday and push across the region more comprehensively on Friday, building a series of overlapping south swells throughout the weekend. 

The latest model guidance has slightly weakened the strength of the two primary fetches - one exiting eastern Bass Strait (providing Saturday’s waves) as well as the primary low tracking underneath Tasmania (providing Sunday’s waves), so I've pulled back wave heights a touch from Monday’s estimate. However, we’ll still see plenty of swell. And, I'm certainly forecasting a lot higher than our computer model is estimating. 

Saturday should build into the 2-3ft range at south facing beaches (bigger near 4ft across the Hunter) whilst Sunday’s swell - even though the responsible fetch will be quite off-axis - should push 4-6ft at south facing beaches, with larger sets north of 6ft to maybe 8ft across the Hunter and other south swell magnets that enjoy long period south swells. Of course if your beach isn't open to the south it'll be a lot smaller (southern ends will be very small). 

A couple of things on Sunday’s swell too: the flukey swell source means that we’ll see a much smaller spread of the upper end of this size range, compared to south swells generated by S/SW fetches parallel to the eastern Tasmanian and Southern NSW coasts. Fronts rounding the Tasmanian corner can often be hit and miss (for NSW surf prospects) but I really like the way this one projects from polar latitudes, it’s just a shame it’s not positioned a few more degrees to the east otherwise we could probably add another two or three feet on to these size estimates.

Local winds could hamper Sunday’s waves anyway. Saturday is looking nice and clean with light winds under a weak troughy pattern, but this trough may evolve into a closed low on Sunday. Current model guidance suggests freshening SE winds for some coasts, so we’ll have to take a closer look on Friday. A windswell is also a possibility depending on how (or even if) this low develops.

Next week (Apr 20 onwards)

Sunday’s possible closed low could generate some punchy local swell for Monday but it’s not yet clear whether this will eventuate. In any case, Sunday’s solid S’ly groundswell will be steadily easing by this time. 

There’s some modest activity happening north of New Zealand in the long term model runs but I’m once again sharpening my focus towards approaching frontal systems below Tasmania next week, that’ll likely maintain a steady stream of southerly swells for the middle to latter part of next week and onwards. 

See you Friday!