Oʻahu Box Jellyfish Probability Calendar (2026)
Monthly box jellyfish arrival dates on Oʻahu south-shore beaches for 2026, derived from the lunar cycle.
Last updated:
Summary
Box jellyfish arrive on Oʻahu south-shore beaches 8-10 days after each full moon, with peak arrival on day +9. The pattern is well-documented by the state lifeguard service and University of Hawaiʻi marine biology research (Chiaverano et al., 2013). South-shore beaches affected include Waikīkī, Ala Moana, Hanauma Bay, Hanauma Bay overlook beach. North-shore + windward beaches show much weaker correlation with the lunar cycle.
Practical advice:on the “arrival window” dates below, check the Honolulu Ocean Safety advisory before swimming at south-shore beaches. Sting severity is moderate; vinegar is the first-line treatment.
2026 arrival calendar
| Full moon | Peak arrival | Arrival window |
|---|---|---|
| 2026-01-04 | 2026-01-13 | 2026-01-12 → 2026-01-14 |
| 2026-02-02 | 2026-02-11 | 2026-02-10 → 2026-02-12 |
| 2026-03-04 | 2026-03-13 | 2026-03-12 → 2026-03-14 |
| 2026-04-02 | 2026-04-11 | 2026-04-10 → 2026-04-12 |
| 2026-05-01 | 2026-05-10 | 2026-05-09 → 2026-05-11 |
| 2026-05-31 | 2026-06-09 | 2026-06-08 → 2026-06-10 |
| 2026-06-29 | 2026-07-08 | 2026-07-07 → 2026-07-09 |
| 2026-07-29 | 2026-08-07 | 2026-08-06 → 2026-08-08 |
| 2026-08-28 | 2026-09-06 | 2026-09-05 → 2026-09-07 |
| 2026-09-26 | 2026-10-05 | 2026-10-04 → 2026-10-06 |
| 2026-10-26 | 2026-11-04 | 2026-11-03 → 2026-11-05 |
| 2026-11-24 | 2026-12-03 | 2026-12-02 → 2026-12-04 |
| 2026-12-23 | 2027-01-01 | 2026-12-31 → 2027-01-02 |
Sources
- Chiaverano LM, Holland BS, Crow GL, Blair L, Yanagihara AA (2013). Long-term fluctuations in circalunar beach aggregations of the box jellyfish Alatina moseri in Hawaii, with links to environmental variability. PLOS ONE 8(10): e77039.
- Honolulu Ocean Safety daily advisories at honolulu.gov/ocean-safety.
- US Naval Observatory full-moon dates for 2026 cross-verified.
License
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). Attribution: “Oʻahu Box Jellyfish Probability Calendar 2026, Holoholo.ai (CC BY 4.0).”