Wellington Marine Forecast — Cook Strait
Updated Tue Jul 28, 2026
NO-GO all three days — rough seas and strong winds
Forecast for Jul 28–30, 2026
📋 NO-GO all three days — rough seas and strong winds
A large ESE swell of 5.5–6.8 feet at 11-second periods makes Tuesday unsafe all day despite light morning winds. A confused cross-sea develops as ESE swell crosses NNW wind-waves, creating unpredictable motion. Conditions deteriorate sharply by evening with winds reaching 23 knots and gusts to 31 knots — NO-GO all day.
Sustained 23–24 knot NNW winds with gusts to 33 knots and 6.0–6.6-foot seas at 7-second periods make Wednesday dangerous all day. A confused cross-sea — ESE swell crossing NNW wind-waves — creates erratic, unpredictable motion with no good heading. High forecast confidence (95%) leaves no doubt: NO-GO all day.
The worst day of the forecast: NNW winds peak at 33 knots with gusts to 45 knots, driving seas to 9.4 feet at a brutal 6-second period. Steep wind-wave chop persists all day with no relief. High confidence (95%) confirms these dangerous conditions — NO-GO all day, stay in port.
A persistent swell train from the ESE/SE combined with building NNW wind-waves creates dangerous and confused sea states across the entire forecast period. Conditions deteriorate progressively from Tuesday through Thursday, with winds peaking at 33 knots and seas reaching 9.4 feet at short 6-second periods on Thursday. There are no safe boating windows across the three-day outlook — stay ashore until this system passes.
Recent days at Cook Strait
About Cook Strait
Wellington's boating is decided outside the heads, not inside them. The harbour is sheltered; Cook Strait is not, and it has a reputation for wind that it comfortably earns. This forecast covers the exposed water south of the entrance — the conditions you actually meet once you're clear.
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 Cook Strait
The strait sits in the gap between the North and South Islands, and that gap does something specific to weather: it funnels and accelerates it. Wind moving through the strait is routinely stronger than the same system either side of it, which is why a forecast that looks unremarkable regionally can still be a hard day on the water here. Treat the strait's own numbers as the ones that matter.
Two things compound it. Tidal streams run strongly through the strait, and wind against tide is what turns a manageable sea into a steep and punishing one — so read wind direction against the tide, not wind speed alone. And a southerly has the whole Southern Ocean behind it, arriving as long-period swell with nothing in the way. Plan the return leg as carefully as the run out; the strait is not a place to be caught deciding late.
Cook Strait forecast FAQ
Why is Cook Strait so windy?
The strait is a narrow gap between New Zealand's two main islands, and it funnels weather through it — wind accelerates as it squeezes through, so conditions in the strait are commonly stronger than the surrounding region's forecast suggests. That's the main reason a Wellington day has to be judged on the strait's own numbers.
Does this forecast cover Wellington Harbour?
No — deliberately. This forecast is aimed at the open water of Cook Strait south of the harbour entrance, because that's what decides whether a trip is on. The harbour itself is considerably more sheltered, and a forecast placed inside it wouldn't tell you about the water you're heading into.
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, tide and sea timing closely. NO-GO means conditions are hazardous for small craft and the trip is best postponed.
More offshore forecasts
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