What to expect for water quality, rainfall, and ocean conditions
Transitional months at Hanalei Bay bring variable water quality. The bay's 360+ cesspool problem and four river discharges mean bacteria can spike quickly with any rainfall. Check conditions before swimming.
May starts the drier season at Hanalei with about 3 inches of rain. The bay begins clearing up. North shore surf calms significantly. Water quality improves but the cesspool problem means bacteria levels near rivers remain higher than at beaches without sewage sources.
Transitional conditions at Hanalei Bay vary widely. Early north swells can arrive suddenly in fall, while spring sees the last of winter surf. The bay is most swimmable closest to the pier area during moderate swells.
Moderate. The shoulder season between spring break and summer offers a good balance of pleasant weather and manageable crowds.
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. In may, rainfall is less frequent but individual storms can still produce contaminated runoff.
When conditions are clear, Hanalei Bay has excellent ocean activities. Check the water quality above, then book with confidence.
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Safe to Swim Hawaii provides water quality information based on publicly available DOH data and seasonal patterns. This is not medical or safety advice. Always check current conditions, obey posted signs, and use your own judgment before entering the ocean. Privacy Policy
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with the Hawaii Department of Health or any government agency. Water quality ratings are estimates based on publicly available testing data and geographic analysis. They are not real-time measurements and may not reflect current conditions.
Always verify current water quality conditions with the Hawaii DOH Clean Water Branch before entering the water.
When in doubt, don't go out. 🤙