Ishigaki (Yaeyama) weather in January

Okinawa-region forum posters generally rate October favorably: it's past the subtropical rainy season and still warm enough for snorkeling, with early October running noticeably warmer than the tail end of the month. The consistent caveat is typhoons - October is technically the winding-down edge of the season, and while the odds of a direct hit drop compared to July through September, posters were clear the risk doesn't disappear entirely, so it's worth checking storm tracking before a trip. Expect warm, humid days rather than anything close to cool.

Forum posters describe April as statistically stable and pleasant, sitting before the rainy season and well ahead of typhoon risk - one local source specifically names April (alongside June) as a genuinely good window for that reason. Sea temperatures run around 20-23C, described by posters as fine for tide-pooling and general exploring but on the cool side for comfortable swimming without a wetsuit. The clear trade-off for visiting before peak season: posters report noticeably lower accommodation costs (some citing roughly half of high-season rates), thinner crowds, and especially clear water for snorkeling and diving even without the warmer swimming temperatures summer brings.