Ishigaki and the Yaeyama islands have a tropical rainforest climate with long summers and mild winters. It’s humid all year round, but the rainy season is one of the shortest in Japan. The most popular season to visit Ishigaki is summer and early autumn (June to October.) To avoid the crowds, it’s strongly recommended to avoid the Japanese holidays such as Golden Week and the school summer vacation.

table of Ishigaki mean temperatures
Mean temperatures for Ishigaki by JMA, 1991-2020. Some numbers have been rounded off for ease of reference.

Below is a summary of Ishigaki’s and the Yaeyama islands climate. This is my personal perspective after living on the island for over 10 years. As in any place, there will be cold years, hot years, rainy years, and sometimes you can find summer in winter, and sometimes winter will come early, or late.
If your goal is a beach vacation with lots of sun, high season (June-October) is the best time to go.

January – February (Winter)

These are the coldest months in Ishigaki. Daytime temperatures will often hover around 20°C but it feels colder because of the humidity and sometimes strong winds. If you are lucky and the sun is out, it’s the perfect season to go hiking or walk around in a T-shirt on an empty beach. Evenings will be cold so make sure to pack a jacket or a warm sweater.
Since the ocean is fairly warm all year round you can still do water-sports if you wear a thicker wetsuit. Beaches are officially closed but no-one will stop you from swimming.
In February, the first cherry blossoms in Japan starts to bloom.

Events: Ishigaki Marathon, Kuroshima Island Cow Festival

March – April  (Spring)

The official beach opening ceremony takes place mid-March and the islands will start to get warmer and warmer. But when the wind blows it can still feel quite cold, especially in the evenings. It’s still a good idea to bring a jacket or warmer sweater. There will be more sunny days with good weather for hiking.

Events: Beach Opening Ceremony, Ishigaki Triathlon

May – June (rainy season/ summer)

The rainy season usually hits in May, it’s the shortest in Japan and only lasts 2-4 weeks. Be prepared for the occasional tropical downpour out of nowhere but there are many sunny hours, often days, between the rains. It is the most humid season in Ishigaki. No matter how good the weather looks in the morning, be sure to bring an umbrella.
When the rainy season finish, summer is finally here!

Events: Hari Boat Race

July – August (Summer)

Hot sunny days and the emerald blue ocean. Life is good!
This is the time for festivals, including Obon and many other local celebrations. The school summer holidays starts in July and the islands are the most busy during these months.

Events: Ishigaki Harbor Festival, Orion Beer Festival, Southern Island Star Festival

September – October (Summer)

Hot sunny days and the emerald blue ocean. Life is good!
Unless a typhoon blows over the Yaeyama islands, September is the month with the highest risk of typhoons. Ishigaki and the other islands will start to cool down by the end of October.

November – December (Autumn)

In the beginning of November, there is still a good chance for warm summer days and there are usually less tourists. By the end of the month it will start to get colder and the beaches officially close. You can still swim at some of them but many people will feel it’s too cold in the air. The ocean stays fairly warm until December.
Depending on the weather, November could feel chilly with strong winds and in December you want to bring a warm sweater for chilly evenings.

Events: Ishigaki Island Festival

Typhoon Season

Typhoons season runs from June to the end of October. The strength and number of typhoons vary every year with an average of 2-3. Be sure to follow safety advice given by your accommodation and stay indoors. If there is no restaurant open inside your hotel, make sure to buy instant cup noodles or other easy food because everything will close. Most typhoons will pass within one day but it can be longer. Waves can be high for several days so do not go near the ocean until you are sure it’s safe.

If a typhoon hits or passes close to Ishigaki ferries and flights will be canceled. If you have a connecting flight, make sure to check what rules apply if you miss your connection. You could also plan your trip so that you have some days in between as a buffer. If your flight from Ishigaki is canceled because of a typhoon, airlines will generally put you on the next available flight. Always check the specific conditions that apply to your flight at the time of booking.

For the latest weather forecasts and typhoon warnings, Japan Meteorological Agency has information in English.