What to expect for water quality, rainfall, and ocean conditions
Windward Oahu receives heavy winter rainfall. Kailua Beach can see elevated bacteria from stream discharge and residential runoff after storms.
December brings peak wet season conditions to windward Oahu. Heavy rainfall events are frequent. Kailua Stream discharge is high and post-rain water quality advisories are common.
Winter trade wind swells can bring moderate surf to the windward coast. Water temperature is around 75-77°F. Conditions vary with trade wind strength. The beach is more exposed to easterly swells.
Extremely high. December through February is peak tourist season driven by holiday travel and mainland winter escapes. Book accommodations and tours well in advance.
The Hawaii Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. In december, this is especially important as wet-season storms can produce heavy rainfall and significant runoff.
When conditions are clear, Kailua Beach has excellent ocean activities. Check the water quality above, then book with confidence.
Tours listed via Viator and GetYourGuide. Safe to Swim Hawaii may earn a commission if you book, at no extra cost to you.
Free alerts when water quality changes at your beach — brown water advisories, bacteria warnings, and all-clear notices.
No spam. Just safety alerts for your trip.
500+ beaches and 25+ hotels across all 6 islands
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. 🤙