Does it rain a lot?
No! Well, ok…admittedly Yakushima is not only Japan's wettest place, it also ranks as one of the world's wettest places! The annual rainfall is between 4,000mm around the coast and 10,000mm in the mountains. (Just to put that into perspective – the notoriously damp UK gets a maximum 2000mm – 3,000mm a year). It is said to rain "35 days a month" on Yakushima. However, don't cancel your trip yet! A more accurate description might be 35 days of rain in ONE day as there are many fine days. It's just that when it rains here, usually it really rains! Luckily, most of the rain falls around the mountain tops and so the inhabited areas of the island around the coastline do not feel like one of the wettest places on the planet. Indeed, the southern area of the island receives a considerably lower annual level of rainfall, equivalent to that of Kagoshima city on the mainland. The mountains affect the island's weather so much that even though it can be raining heavily in one spot, just a few minutes drive away you can find tropical sunshine.
Whatever season you plan to come, if you're going hiking , bring waterproofs with you (including trousers). You can save yourself some luggage space by renting equipment on the island. YES offers a free booking service for renting waterproof gear, boots, poles, alpine gear etc.
No rain, no rainbows!
The Japanese pride themselves as having 4 distinct seasons, but in fact there are 6! The following is a short run-down of the SIX seasons on Yakushima:
1. The Rainy Season
Let's start with the worst one! The rainy season from early June to mid-July is particularly wet with 2 to 3 times the rainfall of other months. You'd be very lucky to be on Yakushima for a few days without getting rained upon during this period. However, the island is well-equipped to deal with torrential downfalls, due to its steep granite mountains and around 250 rivers then the island rarely has a flooding problem. It is still possible to go hiking in the rain, the temperature is warm and the forests look, and smell, great. Make sure you have a good set of waterproofs and boots, and don't forget to double bag everything in your backpack. The one hiking area that can be badly affected by the rain is Shiratani due to the number of river crossings. Therefore on rainy days it is advisable to check if the trails are open and if not then change your itinierary to the Yakusugi Land area which has bridge crossings.
2. The typhoon season!
OK. Not a season as such, but worth a mention. Typhoons approach the island several times a year and one or two hit the island hard every year. The typhoon season usually begins towards the end of the rainy season and can continue up to mid-October. If you come from a country unaffected by typhoons then you may well be concerned about planning a trip during this time. For the Japanese, typhoons are simply a fact of life and though there is always an element of risk in planning your trip during this time, at least you can do so safe in the knowledge that if a typhoon does cause you to change your plans then no cancellation charges will be incurred. If you are planning your trip to Japan during the typhoon season then consider coming to Yakushima first and NOT LAST – just in case there are ferry or flight cancellations off the island.
The summer months are the peak season for Japanese tourists to visit Yakushima and this is for good reason. Temperatures hover around 28 – 30°C during the summer months which, combined with balmy sea breezes, this makes Yakushima a much more comfortable place compared to the sweltering heat on the Japanese mainland. The humidity on Yakushima is high, but with the mountains considerably cooler than the coastal areas, hiking is very popular and the sea, rivers and waterfalls offer a multitude of ways to have fun and stay cool. Don't be surprised if you have the beach all to yourself as well!
The humidity will begin to drop around mid-September and evenings start to feel a little cooler. Autumn is probably the driest season on Yakushima. Once the typhoon season is over (usually early October) the weather can be stunning. Clear blue skies and excellent visibility mean perfect hiking conditions. Even in late October, the temperature can stiil reach 28°C – meaning you may still be able to swim (do expect some strange looks from any passing locals though!). Japanese hikers favour October and the hiking in November is equally good (the trails are much quieter). By November, you will need a warm layer or two especially for trekking and expect the tops of the highest mountains to be under 10°C while the coast still hovers above 20 °C.
Winter has the largest seasonal difference in temperature and climate between the north and south of the island. The northern area is often very grey, damp and cool, while the southern part is significantly drier, sunnier and milder. The whole coastal area is sub-tropical, meaning that the temperature around the base of the island never falls below zero. However, Yakushima is the southernmost place in Japan where there is deep snow in the mountains. January and February are the coldest months when the temperature on the peaks can go as low as -10°C, but feel much colder with the wind chill. To go hiking in to the interior mountains at this time of the year requires alpine equipment (available to rent) and we strongly advise you do not attempt it without a guide as weather conditions can be very changeable. The exterior mountains are more accessible in the winter, Mochomu Dake in the south is close enough to the coast to be snow-free all winter. The popular trekking areas of Yakusugi Land and Shiratani Unsuikyoi can have a light covering of snow, but are usually accessible.
Though the forests of Yakushima are mainly evergreen, spring does come to the island and it arrives with an explosion of a million shades of green. The island has little cherry blossom to see around the coast, but from the end of March to early April you will be able to see the 'yamazakura' (mountain cherry blossom) which cloaks the mountains in a beautiful pink haze. Spring is a mixture of sunshine and rainy days with lots of strong breezes and by the end of April the temperature will be around 20C. May offers beautiful conditions for hiking, but be warned if you happen to be coming during Golden Week – the busiest time of the whole year – make sure to book everything well in advance.
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