#62 How to survive a heat wave in Japan
On hot wet summers in Japan and how to survive and enjoy (?) it
According to the WMO (World Meteorological Organization), last month was the hottest June in recorded history. Japanese weather officials issued a seasonal forecast on June 20, warning of a return of more heat waves in the second half of next week and a once-in-a-decade hot summer. Those who have already booked flights and hotels will not be able to avoid this heat wave, but understanding the unique Japanese heat and taking precautions may help make your summer trip to Japan a little more comfortable.
Heat Waves in Japan
You may think that the Japanese archipelago is very small but the distance between the north, south, east, and west ends of Japan's territory is over 3,000 km, giving Japan a wide range of climates, from subarctic Hokkaido to subtropical Okinawa. That means you can go skiing in the powder snow in the north/highlands of Japan and then go lay on the beach of Okinawa in the same week in April.
However, if you’re visiting major cities like Tokyo, Kyoto, and Osaka, you can expect hot humid summers and heat waves, especially in the urban areas.
Rainy Season (June - July)
The rainy season (or tsuyu 梅雨) refers to the period from early June to mid-July when a seasonal rain front, extending from east to west, stagnates over the Japanese archipelago, resulting in rainy and cloudy weather. Sudden heavy rain can cause serious disasters like flooding while insufficient rainfall during this rainy season can affect summer crop yields. Perhaps due to climate change, there have been instances recently where a month's worth of rain falls in a single day during the rainy season, resulting in severe disasters. The rainy season in Japan is often uncomfortable due to high humidity, with levels sometimes exceeding 80%!
Typhoons
A typhoon (or tropical cyclone) is a low-pressure system that develops in the tropical ocean or the South China Sea. An average of 26 typhoons occur each year, mainly between June and November, and an average of 14.4 typhoons make landfall or approach Japan. Considering that typhoons occur from summer to autumn, the possibility of travelers being affected by typhoons is fairly high. Once a typhoon starts approaching Japan, it will start raining hard with strong wind. You will be affected by typhoons for nearly one week.
An extremely hot summer (end of July - August)
The rainy season is over in the Tokyo area
On the 22nd of July, they announced the end of the rainy season in Kanto and some other parts of Japan. According to the seasonal forecast released by the Japanese weather authority on the 20th of July, we’re looking at a very hot summer this year. Late July to early August will be the hottest time of the year, with "extremely hot" temperatures expected in many areas.
Meteorological authorities are warning of the possibility of a once-in-a-decade heat wave beginning in the second half of next week. In the old days, Hokkaido (northern island) used to be a summer retreat, but it seems that there will be nowhere we can escape the heat this summer.
So what shall we do if we want to escape from the heat this time of the year in Japan?
What to wear in the middle of summer
It is not ideal to wear jeans since the Japanese summer is humid and hot. Thick cotton fabrics stick to your body and keep you wet. Shorts made out of light fast dry fabrics will be handy in summer here. As long as you are staying in big cities, T-shirts and shorts should be fine. A tip would be to bring a thin layer of long sleeves to wear inside trains and buildings with strong air conditioning. You can always buy clothes in Japan so my advice is to not worry too much about what to pack but supply on demand when arriving!
Goods to beat the heat
There are several comfort goods that you may not find outside Japan. Some may seem strange to you, but it might be fun to try them out:
Salt Tablets
Hydration is the priority in Japan's hot and humid climate, but a lack of salt, which is lost through sweating, can cause headaches, dizziness, and fatigue. These tablets are an easy way to recharge potassium, which is lost through perspiration. You can buy them at drugstores and supermarkets.
Cooling spray for clothes
Simply spray on clothes for a refreshingly cool sensation. It also deodorizes and sterilizes the smell of sweat on clothes. It is manufactured by several companies and sold under the product names "Shirt Mist" by Hakugen Earth and "Shirt Hieru" by Don Quijote.
Cooling Pads
The cooling pads sold by Lion, one of Japan's largest health care companies, were originally intended to be applied to the forehead when a child developed a fever, but are now also available for the body, making them convenient for portable use. It is a good idea to have one of these pads not only for hot summers but also for children who are prone to fever. My family also found them useful when our children developed fevers while stationed abroad.
Sport drinks
POCARI SWEAT is a historically popular sports drink in Japan created by Otsuka Pharmaceutical. It’s marketed to be a health drink with electrolyte supplements and they are sold everywhere in convenience stores and vending machines.
My personal favorite is OS1 (Oral Rehydration Solution) produced by the same company. I brought it to my mission in Pakistan, and it worked very rapidly for rehydration. I strongly recommend OS1 for the fatal situation. This can be bought at drug stores.
You’ll also find interesting products and goods that the Japanese people have invented and incorporated into their lives over the years. If you’re coming from a drier cooler climate, it might be an interesting experience!
What to do in case of a heat stroke
There may be exceptional and unwanted cases in which you have to call for an ambulance (dial 119 for emergencies). Recently there are so many heatstroke cases among older people which is slowing down ambulance response time. So make sure to take care of your own health, hydrate, and look out for the first signs of heat stroke symptoms.
Lingering summer heat and long summers
Another recent and pertinent trend is the prolongation of the lingering summer heat. When I was a child, it was cooler in mid-September, and Japanese schools switched to winter uniforms in October. In recent years, however, the lingering summer heat has become noticeably prolonged, with days in October still exceeding 30°C (86°F).
Final words
Don’t underestimate the heat in Japan, don’t wait until you get thirsty, and drink water regularly while you are sightseeing. But also see this as an opportunity to visit the highlands, or somewhere outside of the city and try out the different products and activities Japan has invented over the years to overcome the hot sweltering summer heat.
Grear advice. I'll be guiding a group of tourists twice in August and this information will come handy.