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TREND REPORT

Hawaii Water Quality — July 17, 2026

Oʻahu water quality is worsening (-29pp in 14 days)

BIG ISLAND
Still clear (100% clean)
MAUI
Still clear (100% clean)
OʻAHU
-29pp worsening
KAUAʻI
Still clear (86% clean)

Oʻahu ocean water quality worsened 29 percentage points over the last 14 days (100% clean two weeks ago vs. 71% clean now).

For a trip in the next week, prioritize islands with stronger structural protection (dry coasts, reef enclosure, no major streams). See cleanest Hawaiian island and BWA alternatives.

Where the islands stand today

Big Island

still clear

Big Island has been persistently clear — the same baseline as the prior two weeks. 0 of our 7 tracked beaches on the island have active advisory days in the last 30 days. NOAA's 7-day forecast is mild — scattered showers possible but unlikely to drive new advisories. See the Big Island leaderboard for the beach-by-beach ranking.

Maui

still clear

Maui has been persistently clear — the same baseline as the prior two weeks. 0 of our 6 tracked beaches on the island have active advisory days in the last 30 days. NOAA's 7-day forecast is dry, so the persistently clean baseline should hold. See the Maui leaderboard for the beach-by-beach ranking.

Oʻahu

worsening

Oʻahu is worsening over the last 14 days (-29pp vs. the prior two weeks). Our 12 tracked beaches happen not to overlap with the DOH advisories driving this signal — the worsening trend is from island-wide or other-area advisory events. NOAA's 7-day forecast is mild — scattered showers possible but unlikely to drive new advisories. See the Oʻahu leaderboard for the beach-by-beach ranking.

Kauaʻi

still clear

Kauaʻi has been persistently clear — the same baseline as the prior two weeks. 0 of our 6 tracked beaches on the island have active advisory days in the last 30 days. NOAA's 7-day forecast is mild — scattered showers possible but unlikely to drive new advisories. See the Kauaʻi leaderboard for the beach-by-beach ranking.

NOAA 7-day forecast, per island tourist coast
  • Kohala Coast, Big Island: mild (max 23% chance of rain across next 7 days)
  • South Maui (Wailea / Kihei): dry (max 6% chance of rain across next 7 days)
  • South Shore O’ahu (Honolulu / Waikiki): mild (max 28% chance of rain across next 7 days)
  • Po’ipu, Kaua’i: mild (max 39% chance of rain across next 7 days)

For the always-live per-island outlook, see our Hawaii Water Quality Forecast, which regenerates daily from NOAA + DOH data.

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Methodology: Statistics in this report come from our pipeline's aggregation of Hawaii DOH Clean Water Branch advisory data across 31 tracked beaches (last 14 days compared against the 14 days before). Forecast data from NOAA National Weather Service (api.weather.gov) sampled at each island's primary tourist coast. All numbers accurate as of publication. This report describes water-quality trends and forecast; it is not a swim recommendation. Physical hazards (shore break, rip currents, surf, marine life) are independent of water quality. Always check the individual beach page and local conditions before entering the water.