Live destination decision · Hawaii Island
The island has six very different coasts and they are rarely calm on the same day. This ranks them from four sources that do not agree with each other.
Checking the water
NWS forecast, alerts, wave model and wind.
Loading source freshness…
How the call is made
No score and no hidden weighting. Each coast gets one of three steps, from the worst signal available.
Honest limit: the model alone is a weak judge of danger. Checked against ten years of NWS advisories, the daily peak height separated advisory days from other days only modestly (about 0.76 on Kohala and 0.63 on the south coast, where 0.5 is a coin flip and 1.0 is perfect). That is why the NWS forecast and alerts lead and the model is read against each coast’s own history. The step cutoffs are starting rules and confidence never rises above MODERATE. Brown water after heavy rain, jellyfish and vog are not part of this call.
Source provenance
The questions visitors actually ask
The Kona and Kohala coasts sit in the island’s lee. Mauna Kea, Mauna Loa and Hualalai block the trade-wind swell that hits Hilo and Puna, so the west side is calm for much of the year. Winter north and west swells are the exception, especially on Kohala and North Kona.
It means large breaking waves and strong currents that can sweep people off the shore. Beach parks often close their water access. Treat it as a day to stay out of the water, even on a beach that looks fine from the sand.
No. Calm water can still have rip currents, and a shore break can be dangerous when the height looks small if the swell is long-period. Read the notes on each coast, and swim near a lifeguard where there is one.
The two main sources disagree by two steps, for example the forecast says small and the model says big for that coast. Rather than pick one, the tool tells you to judge the water yourself.
The NWS surf forecast covers about two days and the wave model about four. Days past the forecast rely on the model alone and the page says so.
Not in the call. After heavy rain, runoff can make water unsafe near streams and the Hawaii Department of Health posts advisories. Check them before you swim after a storm.
Hawaii decision tools
This is decision support, not a safety system. Lifeguards, posted signs and the National Weather Service control. Ocean conditions change within minutes. An independent site, not affiliated with any agency.