What to expect for water quality, rainfall, and ocean conditions
The windward coast gets more rain than other parts of Oahu. Waimanalo Beach water quality varies with recent rainfall. Avoid areas near stream mouths after storms.
November brings 4+ inches of rain to windward Oahu. Waimanalo's streams carry agricultural runoff, which includes fertilizers and animal waste from nearby farms. Bacteria risk is elevated near stream mouths.
Winter trade wind swells bring moderate surf to windward Oahu. Waimanalo can see 3-5 foot waves on windy days. Water temperature is around 75-77°F. The long beach has variable conditions along its length.
Moderate. Late fall brings fewer visitors before the holiday rush begins.
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. In november, this is especially important as wet-season storms can produce heavy rainfall and significant runoff.
When conditions are clear, Waimanalo 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. 🤙