Best Time to Dive Yonaguni
Across 2 Yonaguni dive sites with multi-year conditions history, September historically shows the most favorable days — 76% of sampled days in the good band. The next-highest months are August (73%), June (58%) and May (56%). February historically shows the fewest favorable days (12% of sampled days). Average water temperature in the sample runs from about 24°C in February to 30°C in August. Typical seas range from 1.3 m to 2.6 m of significant wave height through the year. These figures are historical climatology computed from measured conditions — patterns, not a forecast or a guarantee.
Computed from our own conditions climatology — measured history, not brochure copy.
Which months are historically most favorable in Yonaguni?
| Month | Historically favorable days | Water temp | Typical seas |
|---|---|---|---|
| Jan | 18% | 24°C | 2.5 m |
| Feb | 12% | 24°C | 2.4 m |
| Mar | 30% | 24°C | 2.0 m |
| Apr | 47% | 26°C | 1.6 m |
| May | 56% | 27°C | 1.6 m |
| Jun | 58% | 29°C | 1.4 m |
| Jul | 49% | 30°C | 1.8 m |
| Aug | 73% | 30°C | 1.3 m |
| Sep | 76% | 30°C | 1.4 m |
| Oct | 34% | 29°C | 2.4 m |
| Nov | 19% | 27°C | 2.5 m |
| Dec | 13% | 26°C | 2.6 m |
% = share of sampled days scoring in the favorable band, median across 2 dive sites with at least two years of history. Ringed = historical peak.
How does this compare worldwide? The Most Reliable Diving Months on Earth ranks 61 countries by the same measure.
Marine life seasons
Sighting patterns across the wider Japan & East Asia region — not site-specific promises.
- Green sea turtleApr–Jun
Bars are Jan–Dec — months when sightings historically concentrate (GBIF occurrence records). Wildlife is never guaranteed.
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