Sydney Hunter Illawarra Surf Forecast by Steve Shearer (issued Fri Dec 21st)

Features of the Forecast (tl;dr)

• Quality S/SE swells Sat with light offshore W-W/NW tending NE winds
• Lots of fun leftovers Sun from the S/SE with light winds- possibly S’ly- tending N/NE and freshening
• Small, background E swells in the mix Fri-Sun
• Dynamic outlook for Xmas week
• Deep low forming in Tasman off Gippsland Coast Mon with a sizey S swell developing Xmas Eve
• Sizey S swells Xmas Day with light winds tending NE in the a’noon
• Easing swells Boxing Day
• NE windswell likely Fri next week
• Easing swells into next weekend and a quiet end to 2024

Recap

S’ly winds hampered wave quality yesterday with around 3-4ft of S swell in the water, easing a notch during the a’noon. Today we are seeing cleaner conditions as pressure gradient ease and land breezes develop. Still a little bit of leftover bump around but workable options across the board with 2-3ft of S-S/SE swell, expected to boost a notch into the a’noon under light S-SE’ly winds.

Offshore winds this morning trying to clean up bumpy but fun S/SE swell

This weekend (Dec21-22)

Still looking good for Sat. Current ASCAT (satellite windspeed) pass shows a Tasman low with a long fetch of strong S-S/SE winds well positioned in the swell window. Concurrently, weak high pressure is moving NE to be off the sub-tropical coast o/night and into tomorrow morning. That will see light winds establish with morning land breezes and light a’noon seabreezes north of Sydney. A weak trough looks to bring a S’ly flow south of Sydney, likely extending into the Illawarra after lunch. This a’noon’s increase should boost further o/night with good quality, mid-period S/SE swell to 3-5ft tomorrow morning, easing back a notch in the a’noon. 

Easing swells continue through Sunday. Leftover S/SE-SE swell should hold some 2-3ft surf at open beaches in the morning, dropping back to 2ft through the a’noon. Winds looks a bit tricky as the remnants of the trough linger about the Central NSW Coast. A light SW-SE flow in the morning is likely to tend light/variable before a’noon N/NE breezes establish and begin to freshen through the second half of the a’noon. 

Next week (Dec23 onwards)

We are getting good model agreement on the Xmas week now, leading to increasing confidence on outcomes. O/night Sun into Mon we’ll see a low form off the Gippsland Coast and begin to deepen rapidly through the morning. An early W’ly flow tends SW and begins to freshen by start of business hours. 

We should see a blend of small NE windswell from winds feeding into the developing low and small S/SE-SE swells from a fetch under the South Island with a window of clean 2 occ. 3ft surf before the winds start to tend more S’ly, although windspeeds look to remain relatively light through the region through the day. A modest increase in new short range S swell should build to 3ft through the a’noon. 

By Xmas Eve we are expecting a deep ( approx. 980 hPa) cut-off low in the Tasman, due east of Tasmania (see below). A steeply angled due S swell will be in the water with a mod SW-S flow. It won’t be giant but we will see sizey, energetic S swells to 4-6ft at S exposed breaks, with a few bommies showing larger sets and smaller surf into more protected locations. 

Current modelling has the low slow moving through Xmas Eve with a thick fetch of SW-S strong winds to low end gales. That should see surf build a notch more into Xmas Day, with size to 6ft+  and bigger sets at open bommies through the morning before an easing trend in the a’noon. Winds look perfect as high pressure drifts over Southern NSW: light land breezes tending to light NE seabreezes in the a’noon. Should be plenty of good, solid surf on Xmas Day as long as you can find somewhere handling the size, especially in the morning.

A fairly rapid easing into Boxing Day as the low weakens and moves NE. Still some sets to 3-4ft, dropping back to 2-3ft during the day. Winds will tend N/NE and freshen during the day with light NW breezes for the morning.

An approaching cut-off low sees NE winds freshen Fri with a corresponding increase in NE windswell expected. We should see N/NE winds freshen and tend N’ly with NE windswells building to 3-4ft. A trough bringing a S’ly change looks to arrive after dark, but we’ll finesse that on Mon.

Easing swells then over next weekend, as the cut-off low gets shunted southwards and high pressure moves into the Tasman. Looks like a quiet run into the New Year from there.

We’ll see how that all looks on Mon. 

Seeya then and have a great weekend!