Sydney Marine Forecast
Updated Fri Sep 11, 2026
Friday's big swell rules out boating; weekend eases but stays choppy
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Marine Forecast for Sydney Sep 11–13, 2026
📋 Friday's big swell rules out boating; weekend eases but stays choppy
NO-GO Friday: light winds but a large 5.5-6.7 ft SSE/S swell at 9-10 second periods keeps seas unsafe all day. Best to wait this one out.
Saturday improves with lighter swell (4.4-4.7 ft SSE) and light winds, but early afternoon (12 PM-4 PM) brings a confused cross-sea as ENE wind-waves cross the SSE swell. Morning and evening are the better bets.
Sunday morning through mid-afternoon looks good with light NE-N wind and a manageable SE swell, but a confused cross-sea builds and lasts about 11 hours as wind-waves cross the swell, peaking in the evening. Plan to be off the water before conditions mix up.
Friday brings large 5.8-6.7 ft SSE/S swell at long 9-10 second periods that keeps wave conditions in the bad-to-caution zone all day despite calm winds, driving the overall NO-GO call. Saturday and Sunday see swell drop into a more manageable 4-5 ft range, but both days develop a confused cross-sea as SSE/SE swell crosses ENE wind-waves generated by building afternoon breeze, producing awkward boat motion that warrants caution during those windows.
Recent days at Sydney
Today’s Water at Sydney
Sea surface temperature and chlorophyll around Sydney, imaged fresh every morning. Water at the star is 63.4°F today, and chlorophyll of 0.2 mg/m³ reads as blue-green transition water at the spot.
Imagery: Sep 10, 2026 · rebuilt every morning
These charts show you the breaks. DeepCast reads them. A zone-by-zone AI fishing report for these exact waters — temperature edges, color changes, and structure, analyzed together — for $4.99.
Get the AI fishing reportSST and chlorophyll from the SeaLegs AI DeepCast satellite pipeline. Charts are a planning aid — always check the official marine forecast before making the run.
About Sydney
Sydney's coastal water is exposed, and the thing that most often decides a day here is not the morning conditions but how fast they change. The outlook below is built around that: wind, swell and sea state across the next few days, so you can see whether a window holds.
It updates every morning from the latest marine model data, and each day gets an honest GO, CAUTION, or NO-GO call — the same AI rating used in the SeaLegs AI app.
Reading Sydney's coastal waters
From roughly October to February, the pattern to respect is the southerly buster — an abrupt southerly change that runs up the NSW coast, typically arriving late afternoon or early evening after a hot day. The stronger ones bring peak gusts of 40 knots or more, with wind swinging from light and northwesterly to a hard southerly within minutes and the temperature dropping sharply at the same time. Gusts usually ease within 30 to 60 minutes of arrival, but that is more than long enough to turn a pleasant afternoon into a serious one if you're offshore and heading south.
Worth knowing: a true buster is a specific event, not just any southerly change. Ordinary southerly changes are common and far milder. Either way the practical lesson is the same — on a hot day with a light northerly, treat the afternoon as borrowed time and plan to be back in before the change. Read the whole window below, not just the hour you'd leave.
Sydney forecast FAQ
How is the sea at Sydney today?
As of Sep 11, 2026, the SeaLegs AI verdict for Sydney is NO-GO. Friday is a NO-GO day: while winds stay light and pleasant at just 3-7 knots from the W to E through the day, a persistent 5.5-6.7 ft swell at 9-10 second periods from the S/SSE keeps sea state in the bad-to-caution range around the clock. Even though the long period suggests organized swell rather than chop, the sheer height makes conditions unsafe for recreational vessels, especially in the early morning hours (12:00 AM-4:00 AM) when waves peak near 6.7 ft. Visibility is good, but this is a day to stay ashore and let the swell subside.
What is a southerly buster?
It's an abrupt, strong southerly change that charges up the New South Wales coast, mostly between October and February, usually reaching Sydney in the late afternoon or early evening after a hot day. Strong ones gust over 40 knots and drop the temperature sharply within minutes. It's a specific pattern — stronger and more sudden than an ordinary southerly change — and the gusty phase typically eases within 30 to 60 minutes.
How accurate is this Sydney marine forecast?
The outlook is generated from the latest marine model data and rated GO, CAUTION, or NO-GO by the same AI engine used in the SeaLegs AI app. It's a planning aid, not a substitute for the Bureau of Meteorology's coastal waters forecast and marine warnings — always check those, especially when a change is forecast.
How often is this forecast updated?
The page is rebuilt every morning from the latest model run, and the SpotCast card refreshes live in your browser. The date stamp above the outlook shows when it was last generated.
What do GO, CAUTION, and NO-GO mean?
GO means conditions are favourable for most recreational boats. CAUTION means marginal — manageable for experienced crews in capable vessels, but check the wind and sea timing closely. NO-GO means conditions are hazardous for small craft and the trip is best postponed.
What is the water temperature at Sydney today?
As of Sep 10, 2026, the satellite-derived sea surface temperature at Sydney is about 63.4°F, with chlorophyll around 0.2 mg/m³ (blue-green transition water). The SST and chlorophyll charts on this page are rebuilt every morning from the SeaLegs AI DeepCast satellite pipeline.
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