The climate of Ishigaki and the Yaeyama archipelago as a whole is classed as being semi-tropical, which is distinct from mainland Japan's climate which is temperate. Consequently, visitors can enjoy warm weather virtually all year round. UV exposure is high, so taking the precaution to apply high-factor sunblock is advisable, even on cloudier days. The tables below detail the average recorded temperatures for Ishigaki island.
Degrees Centigrade
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average 18.3 18.6 20.6 23.2 25.5 27.9 29.3 28.9 27.7 25.6 22.8 19.8
Average High 20.9 21.1 23.2 25.8 28.1 30.3 31.8 31.5 30.5 28.4 25.4 22.4
Average Low 16.1 16.4 18.3 21.0 23.5 26.0 27.3 26.8 25.5 23.5 20.6 17.7
Degrees Fahrenheit
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average 64.9 65.5 69.1 75.8 77.9 82.2 84.7 84.0 81.9 78.0 73.0 67.6
Average High 69.6 70.0 75.8 78.4 82.6 86.5 89.2 88.7 86.9 83.1 77.7 72.3
Average Low 60.1 61.5 64.9 69.8 74.3 78.9 81.4 80.2 77.9 74.3 69.1 63.9

The figures above are based on average measurements recorded by the Japan Meterological Agency through the period 1971-2000.

Long summers

Sukuji beach on May day morningTo somebody who lives in a cooler, temperate climate, Ishigaki's summers can appear to be never ending. By the end of May temperatures are reaching 30°C and the warm weather can continue on until December.

During a one or two week break you can expect to enjoy many dry, warm days on the island with plenty of opportunities to enjoy the many sights and beaches. The length of the day varies little during the year with daylight hours being between around 6.00am and 8.00pm in the summer.

In measurement terms the island gets a lot of rain, however, it tends to arrive in the form of short heavy showers rather than days of persistent rain, hence, travellers shouldn't worry too much about it interfering with plans.

Short winters

Ishigaki's winters are short and mild with temperatures reaching the mid twenties on the warmest days. Even on the coldest days the temperatures rarely drop below 16°C, hence, the standard image of winter is definitely not one which really applies to Ishigaki (if you imagine a British summer you're more likely to be on the right lines). January and February are considered to be the most wintery months, consisting of a mix of dull, rainy days, and clear, sunny days.

Rainy season

The rainy season begins in the middle of May and lasts for between two and four weeks. Although a lot of rain falls during this period it will be intermingled with days of dry, sunny weather, and those who are prepared to take the risk and travel to Ishigaki during this time may be pleasantly surprised. However, be warned that this is one of the most humid periods of the year.

Typhoon season

Ishigaki's typhoon season runs from the start of July to the end of October during which time there is the possibility of typhoons hitting the island. However, the number and severity of typhoons varies from year to year. If you are unlucky enough to be on the island when a large typhoon hits then you can expect to be stuck indoors for at least a day. Naturally ferries to outer islands are cancelled during typhoons and air traffic to and from Ishigaki comes to a standstill.

Click here for some first-hand info about what it's like to experience an average typhoon on Ishigaki island.

Warm waters

The temperature of Ishigaki's costal waters range from around 21°C  in winter to about 29°C in the summer. This makes diving and snorkeling activities which can be comfortably enjoyed throughout the year. It is these warm waters along with the opportunity to view manta ray throughout the year have made Ishigaki a prime dive destination.

A Foreigner's Perspective

After having lived on Ishigaki for almost 2 and a half years I decided that it was about time that I described my experience of living in Japan's southernmost city. To put things in context, I'm a Brit, so I've suffered my fair share of miserable weather (although in all fairness Britain's climate isn't half as bad as people would have you think). I've visited a fair few countries in my time, and speaking personally, I'd probably say that southern-European countries such as Spain offer most agreeable climates. That said, let's move on to Ishigaki.

December – February

Speaking as a resident this is one of my favourite periods of the year. Yes, there are a fair few grey miserable days, but when the sun comes out the weather is every bit as nice as it is in the summer, but without the intense heat and humidity. Having said that, the 2010-2011 winter was particularly cold, with temperatures as low as 10 degrees (Centigrade) being recorded on the island at night. We also experienced a few weeks of absolutely appalling weather, and naturally it was the tourists who suffered the most.

So for residents at least, winter can actually be very pleasant – when it's nice I got out and enjoy weather which is far better than that which I'd be able to find in Europe during the cooler months, and when it rains I stay in and get on with business. However, I'd probably think twice about visiting the island in the winter as a tourist as there's a reasonable chance that you'll hit a run of miserable days, not to mention the fact that the sea will be at its coolest.

March – May

By early March summer starts to provide warnings of its inevitable return – that's right, if you're used to a temperate climate then Spring may feel more like a summer on Ishigaki island. The ocean begins to warm up, the winter waves to the north of the island begin to subside, and you occasionally get runs of very warm / hot days. On the whole I find the weather during this period to be very pleasant, although perhaps not as predictable as that of the summer. Much like Oct-Nov, this is a great time of year to do a bit of trekking as the islands jungle / forest trails are far less humid and relatively free of insects and spiders.

June – September

By the beginning of June the heat of the summer is really starting to kick in, and by mid-July it' can I best describe it...intense. Before moving here I compared Ishigaki's climate statistics to those of other mild countries which I'd visited, such as Spain and Greece, both of which can get very hot during the summer. On paper at least Ishigaki sounded like a walk in the park, after all, even England can see temperatures hit the mid-thirties during the summer.

However, I'd forgotten to take into account the most important factor – humidity. Humidity takes heat perception to a whole different level, and it makes Ishigaki an extremely hot and sticky place during the warmer months. Don't get me wrong; if you plan on spending most of your days outdoors, perhaps lounging on the beach or bathing in the ocean, then the heat is unlikely to represent a problem, indeed, most tourists absolutely adore it. However, speaking as a resident, the heat can really wear you down, not least because you know that there's unlikely to be any respite until late September. That reminds me of another word which I often use to describe Ishigaki's summers – 'relentless'. Not only is it hot for around four months straight, but night time temperatures may only drop by as little as two degrees.

Even basic activities can result in discomfort – I was never a big sweater in England (sorry...too much information?), but here even a relaxed walk to the shops can result in me feeling the need to change my T-shirt by the time I get back home. Step out of an overly air-conditioned supermarket in mid-summer and the wall of heat waiting outside hits you like a kick to the groin. Another inconvenience is having to apply sun cream every single time I go out. The UV on Ishigaki is absolutely brutal for much of the year (even during the cooler months), and even limited exposure can result in significant sunburn, not to mention obvious long-term health risks.

September would probably be my favourite summer month owing to the fact that both the humidity and temperature have fallen off enough to make things a little more comfortable. Naturally there's still the risk of a typhoon, and trust me, once the initial novelty has worn off they are no fun whatsoever.

One of the best things about the summer months is the temperature of the ocean, which peaks at around 30 degrees. I've spent many hours snorkeling and kayaking without experiencing even the slightest chill.

October – November

The weather in October and November is rather hard to call. When I first arrived on Ishigaki I often heard people say that October is the best month to visit the island. However, I remain unconvinced, partially due to the terrible weather which we experienced during October 2011 – not only were we hit by a late typhoon, but the island suffered four or five days of torrential rain. I received some statistics from the council which indicated that over a quarter of the island's average rainfall fell in just a few days, causing huge landslides around the island. The great thing about this time of year is that the good days are incredible, plus, the humidity has dropped significantly and the ocean is still fairly warm.