When is box jellyfish season on Oʻahu?
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Box jellyfish arrive on Oʻahu south-shore beaches 8-10 days after each full moon, peaking on day +9. There's no "season" — they arrive predictably with the lunar cycle year-round. See the 2026 calendar at /data/oahu-box-jellyfish-calendar-2026 for specific arrival windows.
Topics: safety, beaches, data