Beaches that recover first, beaches to avoid, and alternatives when you canʻt swim.
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. After heavy rain on O'ahu, bacteria levels can exceed safe thresholds by 10-100x. The 72-hour countdown begins when rain STOPS, not when it starts.
These beaches are on dry leeward coasts with good ocean circulation. They tend to return to acceptable water quality within 48-72 hours after rain stops:
Ko Olina lagoons (leeward, dry side), Ala Moana Beach (moderate, good flushing), Waikiki east end (Kaimana Beach, farther from Ala Wai).
These locations have stream mouths, chronic contamination, or poor flushing that keeps bacteria elevated longer:
Waikiki west end (Ala Wai Canal mouth), Kailua north end (Kawainui Marsh), Kaneohe Bay (always murky after rain), North Shore stream-adjacent beaches.
The clock starts when rain STOPS, not when it starts. If rain continues intermittently, the countdown resets each time. During the 72-hour window, bacteria counts can be 10-100x above the 130 CFU/100mL advisory threshold. Even if the water looks clear, microscopic contamination may persist.
Pearl Harbor & USS Arizona Memorial, Bishop Museum, Iolani Palace, Waikele Premium Outlets, Diamond Head hike (rain clears, but trail may be slippery), Lyon Arboretum.
Top-rated experiences in the area.
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⚠️ 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. 🤙