Perth Marine Forecast
Updated Tue Jul 28, 2026
Caution advised Tue–Thu; best window Thursday
Forecast for Jul 28–30, 2026
📋 Caution advised Tue–Thu; best window Thursday
Caution all day Tuesday due to persistent 5.0–5.6ft SW swell at 12–13-second periods, despite moderate 7–15-knot east winds. No improvement window exists — the swell stays elevated throughout the full 24 hours. Consider waiting for Wednesday or Thursday.
Caution Wednesday, especially midnight to 4:00 AM AWST when steep wind-wave chop and a confused cross-sea (WSW swell crossing NNE wind-wave) make for uncomfortable conditions. After 4:00 AM, swell eases steadily to 3.8ft at 13-second periods with lighter ENE winds — a workable window for those with a mid-morning start.
Thursday is the best day of the three, with near-calm winds and 3.5–3.9ft SW swell at 13–14-second periods making for comfortable, well-organized seas from mid-morning onward. A brief early cross-sea (WSW swell crossing N wind-wave) clears by mid-morning. The 8:00 AM–12:00 PM AWST window is the top pick of the forecast.
All three days carry a CAUTION rating driven primarily by elevated SW swell and cross-sea interactions rather than wind, which remains moderate throughout the period. Tuesday sees persistently large SW swell keeping waves in the caution range all day, while Wednesday and Thursday improve progressively as the swell eases. Thursday offers the cleanest conditions of the three days, though a brief cross-sea interaction early in the day warrants awareness. Forecast confidence is high across the board (88–95%), so these conditions are well-established.
Recent days at Perth
About Perth
Boating out of Perth runs on a clock. Through the warmer months the morning is usually the calm part of the day and the afternoon belongs to the Fremantle Doctor — the southwesterly sea breeze that arrives with near-daily reliability and turns the water over.
The outlook below 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 the Fremantle Doctor
The Doctor is a southwesterly sea breeze that commonly blows 15 to 20 knots and typically sets in somewhere between late morning and mid-afternoon — often around the early afternoon — and it is at its strongest in December and January, when the temperature difference between land and sea is greatest. It is welcome relief ashore. On the water it means a short, building chop through the afternoon.
The practical consequence is that Perth days are usually decided by timing rather than the daily average. A forecast that reads moderate across the day can still offer a genuinely calm morning window and a difficult afternoon one. If you're heading offshore, plan to be well on your way back before the breeze fills in, and read the hour-by-hour trend below rather than the day's headline number.
Perth forecast FAQ
What is the Fremantle Doctor?
It's the southwesterly sea breeze that blows into Perth on most warm-season afternoons, commonly at 15 to 20 knots. It usually arrives somewhere between late morning and mid-afternoon and is strongest in December and January. For boaties it's the main reason mornings are typically the calmer part of a Perth summer day.
How accurate is this Perth 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 before heading out.
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.
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