Wailea, Makena, Kihei, Kamaole — Maui’s driest coast where citizen science adds an extra layer of monitoring.
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Source: Hawaii DOH Clean Water Branch · Updated automatically
South Maui stretches from Maalaea in the north through the Kihei corridor, past the Wailea resort area, and down to Makena and La Perouse Bay. This leeward coast sits in the rain shadow of Haleakala, receiving only 10–15 inches of annual rainfall — making it the driest part of Maui and one of the driest in the state.
The dry climate is a major advantage for water quality. Fewer rain events mean fewer stream discharge events and less bacteria transport to the ocean. South Maui also benefits from the Hui O Ka Wai Ola citizen science monitoring program, which provides more frequent water testing data than the state DOH alone.
Key contamination sources: Storm drains in the Kihei corridor, small intermittent streams (gulches) that flow only after heavy rain, construction runoff from ongoing development, and injection wells used for treated wastewater disposal (a known issue in Maui).
Source: NOAA climate normals; USGS stream data; Hawaii DOH CWB
Ranked by overall water quality risk. Dry weather baseline; all beaches see increased risk after rain.
Summer (May–September): Almost no rainfall. South Maui beaches are at their cleanest. Calm conditions for snorkeling at Wailea and Makena. Water temperatures are 79–82°F.
Winter (October–March): Occasional Kona storms can bring rain to the leeward side. When these events occur, the dry gulches flash-flood briefly and carry accumulated debris and bacteria to the ocean. Kihei beaches are more affected than Wailea and Makena. South swells can increase wave energy at Makena.
Whale season (December–April): South Maui is prime whale-watching territory. Humpback whales frequent the shallow waters between Maui and Lanai. Beach conditions are generally excellent during whale season.
South Maui’s dry gulches (intermittent stream channels) are dry most of the year but can flash-flood after heavy rain. When this happens, they carry months of accumulated sediment and contaminants to the ocean in a concentrated pulse.
Kihei (Kamaole parks): Several gulches cross the Kihei corridor and outlet near the Kamaole beach parks. After heavy rain, avoid these beaches for 48–72 hours, especially near visible runoff channels.
Wailea & Makena: Better stormwater management and fewer drainage channels. These beaches typically recover within 24 hours of rain stopping. Makena (Big Beach) is rarely affected by runoff.
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Free alerts when advisories change on Maui beaches.
Hawaii DOH Clean Water Branch — Beach monitoring, advisories. eha-cloud.doh.hawaii.gov
USGS — Stream gauge data, rainfall records.
NOAA / NWS — Climate normals, weather patterns.
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent project — not affiliated with any government agency. Water quality assessments are based on publicly available data. They are not real-time measurements. Conditions change rapidly, especially after rain.
Always verify with the Hawaii DOH Clean Water Branch before entering the water.
When in doubt, don’t go out.