What to expect for water quality, rainfall, and ocean conditions
Dry season keeps urban runoff minimal. The lagoon water quality improves with less rainfall. However, the semi-enclosed lagoon always carries slightly higher baseline bacteria than open-coast beaches.
September remains dry but occasional tropical disturbances can bring brief rain. The lagoon's limited flushing means any sudden storm can cause a quick bacteria spike.
The reef-protected lagoon at Ala Moana is calm and warm (79-80°F) in summer. Small south swells occasionally break on the outer reef but the inner lagoon stays flat. Conditions are ideal for families and casual swimming.
Moderate to low. Fall shoulder season offers fewer tourists while conditions remain good. This is one of the best value periods for visiting Hawaii.
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. In september, rainfall is less frequent but individual storms can still produce contaminated runoff.
When conditions are clear, Ala Moana Beach 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. 🤙