There are hot summers, and then there is Japanese summer.

If you have recently moved to Japan from somewhere with relatively dry summers, you may look at a forecast of 32°C and think, That’s hot, but manageable. Then you walk outside and discover that the air itself appears to have become soup. Japan’s summer heat is not only about temperature: high humidity, strong sunlight, warm nights, long walks to train stations, concrete and asphalt radiating heat back at you, and buildings with wildly inconsistent air-conditioning all combine to make July and August surprisingly exhausting.

More importantly, the heat can be dangerous. Heat illness, or 熱中症 (necchūshō), is a major public-health concern in Japan, and the Ministry of the Environment publishes daily heat-risk information using the WBGT (Wet Bulb Globe Temperature). Unlike the temperature on your weather app, WBGT takes humidity and radiant heat into consideration as well.

Fortunately, Japan also has an impressive arsenal of ways to survive summer. Some involve modern refrigeration technology, some involve carrying an umbrella around when it isn’t raining, and some involve purchasing increasingly elaborate devices to attach to your neck.

Eventually, all of them start to seem completely reasonable.

Don’t Look at Temperature Alone

One of the easiest mistakes to make during your first Japanese summer is checking the temperature and assuming you know what the day will feel like. A forecast of 33°C does not really communicate what it feels like to walk twenty minutes to a station while the sun is bouncing off the asphalt and the humidity is preventing your sweat from evaporating efficiently.

Instead, get familiar with the 暑さ指数 (atsusa shisu), or WBGT. The Ministry of the Environment classifies a WBGT of 25–28 as a warning level requiring frequent breaks, 28–31 as a severe warning where strenuous exercise should generally be avoided, and 31 or above as a danger level where exercise should normally be stopped. The ministry’s Heat Illness Prevention Information website publishes local readings and forecasts, as well as Heat Stroke Alerts.

This is especially worth checking before sports days, hikes, festivals, gardening, cycling trips, or ambitious sightseeing itineraries. Your individual condition matters too: the Ministry notes that heat risk is influenced by the environment, physical condition, and activity level, and recommends gradually acclimatizing yourself to hot weather rather than suddenly undertaking strenuous activity.

Yes, You Should Use the Air Conditioner

There is an odd rite of passage among some foreigners in Japan where they spend their first summer staring nervously at the AC remote and imagining a ¥40,000 electricity bill.

You will not get a medal for turning your apartment into a terrarium.

If you have air-conditioning, use it when conditions warrant it, particularly during extreme heat and at night when the apartment remains dangerously warm. Heat illness can occur indoors as well as outdoors, and Japan’s Ministry of the Environment specifically advises people to monitor indoor temperatures during hot weather.

You can make your AC work more effectively by closing curtains or shades against direct sunlight, closing windows while the unit is running, circulating cooled air with a fan or circulator, and cleaning the filters regularly. If your unit has 除湿 (joshitsu, dehumidification) or ドライ (dry) mode, that can also make a humid room much more comfortable, although exactly how dry mode operates varies between models.

A fan or circulator is particularly useful because cool air tends to collect near the floor and around the AC itself. Rather than setting the AC several degrees colder, try moving that air around the room first.

But What If Your Apartment Doesn’t Have Air-Conditioning?

This is not merely a hypothetical problem. Some older Japanese apartments, dormitories, staff housing, and rental properties either do not have air-conditioning or make installing a conventional unit difficult. You may have no suitable outdoor space for a compressor, no existing pipe hole in the wall, or a landlord or building manager who will not permit new holes to be drilled. This was my situation for 5 years.

If that is your situation, the goal is no longer simply “make the room colder.” You want to stop heat entering the room, remove as much accumulated heat as possible, reduce humidity, move air across your body, and create at least one relatively cool part of the home.

Start with the windows. Direct sunlight pouring through glass can rapidly heat a room, so close blackout or thermal curtains during the day, particularly on south and west facing windows. Japanese home centers also sell すだれ (sudare), bamboo screens, and exterior sun shades. Exterior shading has an advantage over curtains because it intercepts sunlight before it passes through the glass and warms the interior.

If outside air is cooler than the apartment in the early morning or evening, open windows on opposite sides of the home where possible and use fans to create cross-ventilation. One surprisingly effective setup is to point one fan out of a hot window so that it exhausts warm indoor air while another window allows cooler air to enter. Once the outdoor temperature climbs above the indoor temperature, however, close the windows again and block the sun.

Fans work best when they are cooling people, rather than simply stirring hot air around an empty room. Put one near wherever you actually sit or sleep. A damp cooling towel around your neck, cool shower, chilled drinks, and lightweight clothing can make that airflow substantially more effective.

Humidity also matters. If you own a dehumidifier, reducing indoor humidity may make the room feel considerably less oppressive, although dehumidifiers themselves release heat while operating. They are therefore most helpful where moisture is a major problem or when used alongside another cooling strategy rather than treated as a substitute for an air conditioner.

At night, concentrate on cooling the bed rather than the entire building. Japan sells a huge range of 接触冷感 (sesshoku reikan), or cool-touch, mattress pads, pillowcases, and blankets. You can also use an ice pillow or wrapped cold pack, a lightweight towel blanket, and a fan positioned to move air across the bed. If one room remains significantly cooler than the others, there is also absolutely no rule requiring you to sleep in the room officially designated as the bedroom.

Most importantly, recognize when DIY cooling is no longer enough. If your home remains dangerously hot during a heat wave, spend part of the day somewhere air-conditioned: a library, shopping center, café, community facility or designated cooling shelter. The Ministry of the Environment maintains information on designated クーリングシェルター (Cooling Shelters) as part of Japan’s heat-illness prevention system.

Buying an Air Conditioner in Japan: The Normal Kind

If you own your home or have permission to install one, the most effective long-term option is usually the standard Japanese split air conditioner, commonly just called an エアコン.

This is the familiar system with a rectangular indoor unit mounted high on the wall and an outdoor compressor unit called the 室外機 (shitsugaiki). Pipes, electrical wiring and a drainage hose connect the two through a hole in the wall.

Buying one is slightly different from purchasing an ordinary appliance because you are really buying an appliance plus an installation job.

Before going shopping, take photographs and measurements of the proposed installation area. You want to know the size of the room in 畳 (jo/tatami), whether there is already a circular AC pipe hole in the wall, whether there is an AC-specific electrical outlet near the ceiling, what that outlet looks like, and where the outdoor unit could sit. Retailers such as Bic Camera specifically ask customers to check the pipe opening, dedicated outlet, plug type, indoor mounting space and outdoor-unit location before purchase.

The outlet is especially important. Japanese air conditioners generally use a dedicated electrical circuit, and different models may require different outlet shapes or 100V versus 200V power. If there is no dedicated outlet or the existing one is incompatible, electrical work may be required. Bic Camera, for example, currently lists dedicated-circuit installation from ¥15,400, although actual costs vary by retailer and building.

Next comes installation. When you buy from an electronics retailer such as Yamada Denki, Bic Camera, Edion, Nojima or similar stores, you will normally arrange an installation date as part of the purchase. A technician brings or installs the indoor unit, connects it to the outdoor unit, runs the refrigerant piping and drainage, and tests the system.

“Standard installation” usually assumes a relatively easy setup: indoor and outdoor units on the same floor, the compressor sitting on the ground or balcony, and only a limited amount of piping. Nojima, for example, defines its standard job as the indoor and outdoor units being installed on the same floor with the outdoor unit floor-mounted and no more than four metres of piping. Anything more complicated can cost extra.

Extras can include longer piping, mounting an outdoor unit on a roof or wall bracket, decorative pipe covers, electrical modifications, removing an old unit, or drilling through difficult wall materials. As one current example, Nojima lists standard installation for smaller 6–10 tatami units at around ¥20,350, while larger units cost more; retailers differ, and some advertise the installation fee as already included in the appliance price.

The potentially awkward part for renters is the hole in the wall. If your apartment already has a pipe opening, installation may be straightforward. If it does not, do not simply authorize the installer to drill one. Edion explicitly notes that tenants should check their rental agreement before requesting a new hole, and different building materials can require additional work and fees.

There is now another complication with older buildings: drilling or enlarging an AC hole can trigger legally required asbestos-related preliminary inspection procedures. Retailers including Bic Camera and Nojima specifically warn customers about this, and some installers will not drill into certain older or unknown structures at all.

For a rental, therefore, the sensible order is:

1. Check whether there is already an AC installation point.
2. Check your lease.
3. Ask the landlord, management company, or employer for written permission if modifications are needed.
4. Photograph the wall, outlet, pipe hole and outdoor-unit location.
5. Take those photographs and measurements to the appliance shop.
6. Choose a unit rated for approximately the correct room size.
7. Arrange installation through the retailer.

Do not buy the giant 18-tatami super-AC first and discover afterward that your apartment has a 100V outlet, nowhere to put the outdoor unit, and a reinforced concrete wall nobody is willing to drill through.

The Rental-Friendly Alternative: Window Air Conditioners

If a normal wall unit is impossible, look for a 窓用エアコン (mado-yo aircon), or window air conditioner.

These units mount directly into a window opening rather than using a separate outdoor compressor. Manufacturers market them specifically for rentals and rooms where conventional AC installation is difficult. Toyotomi, for example, describes its current window units as requiring no outdoor compressor and no wall construction, and explicitly recommends them for rental homes where standard air-conditioning cannot be installed.

They are not tiny (the current Haier JA-W18B weighs about 21.5 kg) but they can provide genuine refrigerated cooling without drilling a large pipe hole through the building. Haier’s current unit is designed for roughly 4.5–5 tatami in a wooden building or 7–8 tatami in a more insulated structure and runs from ordinary 100V power.

The catch is that your window needs to be compatible. There are minimum and maximum dimensions, and you need somewhere for the back of the unit to release heat outdoors. Manufacturers also warn that the exterior side needs adequate ventilation and should not exhaust hot air directly toward a neighboring window.

They can also be relatively noisy because the compressor is effectively sitting in the window rather than several metres away on the balcony. Still, for a bedroom in an apartment where the landlord refuses to permit a normal AC, they can be a genuinely useful solution.

I would still ask your landlord or management company before installing one. “No wall drilling required” does not necessarily mean “your particular rental contract permits absolutely anything attached to the window.”

Portable Air Conditioners: Useful, With One Very Important Catch

The other alternative you will see in Japanese electronics shops is the ポータブルクーラー, スポットクーラー, or portable air conditioner.

Unlike a normal fan, a true portable air conditioner contains a compressor and can actually refrigerate air. Some current Iris Ohyama models are rated for rooms of around 4.5–7 tatami, while larger models cover more space. They plug into 100V power and do not require permanent professional AC installation.

This makes them particularly attractive for rentals, kitchens, old buildings and rooms where no conventional air conditioner can be fitted.

There is, however, one extremely important piece of physics that marketing photographs occasionally make easier to overlook: the heat has to go somewhere.

A portable AC produces cool air from the front and hot exhaust from the back. If you simply put the machine in the middle of a sealed room, it cannot magically destroy heat. Iris Ohyama specifically warns that exhausting the hot air into the same room will actually raise the room temperature and recommends using the exhaust duct.

Most proper portable units therefore come with a large flexible exhaust hose and a window panel. You partially open the window, install the panel into the gap, connect the exhaust hose and send the hot air outside. Iris Ohyama’s current models, for instance, include window panels and exhaust ducts, with optional longer panels available for tall windows.

They are easier to install than a split AC, but “portable” is doing some generous linguistic work here. Many weigh around 20–30 kg, occupy a fair amount of floor space and make considerably more noise than a wall-mounted air conditioner.

They can nonetheless be an excellent compromise if your lease prohibits drilling but you desperately need refrigerated cooling. Just measure the window first and check whether the supplied panel actually fits it.

Also be careful not to confuse a true portable air conditioner with a small 冷風扇 (reifusen), evaporative cooler or desktop “personal air cooler.” Those devices use water or ice to make the air blowing directly at you feel cooler, but they do not refrigerate an entire room. In Japan’s already-humid summer climate, adding additional moisture to the air may also limit how useful an evaporative cooler feels. They can be pleasant when pointed at your face; they should not be treated as substitutes for an actual AC during dangerous heat.

Fans Are Your Friends

Japan sells fans in approximately seventeen thousand forms: standing fans, desk fans, circulators, clip-on fans, handheld fans, neck fans and tiny rechargeable devices apparently designed for the sole purpose of helping commuters contemplate their existence on a train platform in August.

They are genuinely useful, particularly when paired with air-conditioning. A サーキュレーター (circulator) is designed to move air farther across a room and can help distribute cool air from an AC into adjacent spaces. Even without AC, directing airflow across your skin can make you considerably more comfortable because it helps sweat evaporate.

During extreme indoor heat, however, a fan should not give you false confidence. Moving dangerously hot air around does not actually lower the room temperature. If you cannot keep yourself cool and begin to feel unwell, go somewhere cooler.

Become a Person Who Owns a Sun Umbrella

You may arrive in Japan thinking parasols are an accessory for fashionable elderly ladies.

By August, you will understand.

A 日傘 (higasa), or sun umbrella, creates portable shade over your head and upper body. Look for one labelled UVカット (UV blocking), 遮光 (shako) (light blocking), and ideally 晴雨兼用 (seiu kenyo), meaning it can be used for both sun and rain.

That last feature is particularly useful because Japanese summer weather has an impressive ability to transition from “surface of the sun” to “violent thunderstorm” with little notice.

A hat is useful too, but the parasol has the advantage of keeping direct sun off your head, face, neck and shoulders without trapping additional heat against your skin.

Learn the Japanese Summer Drugstore Arsenal

Every year Japanese drugstores, convenience stores, home centers and ¥100 shops sprout seasonal displays containing increasingly inventive ways of making humans colder.

Cooling body wipes (冷感シート) are among the easiest recommendations. They remove sweat and usually contain menthol or similar ingredients that leave your skin feeling temporarily cool, which makes them excellent after a walk to school or work. Clothing cooling sprays, chilled neck rings, cooling towels and portable fans can also make commuting substantially less miserable.

The humble タオルハンカチ, or small hand towel, deserves a place in your bag too. It has no batteries, proprietary cooling polymer, or anime collaboration attached to it. It is nevertheless one of the most useful objects you can own during a Japanese summer.

Dress for the Climate You Actually Live In

Summer is not the season for polyester and optimism.

Loose, lightweight clothing makes an enormous difference. Linen, thin cotton, rayon blends and moisture-wicking fabrics are all worth experimenting with, and Japanese shops sell plenty of clothing specifically intended for hot, humid weather. A moisture-wicking undershirt can seem counterintuitive (surely the solution to being hot is fewer clothes) but it can stop your work shirt from spending the entire day glued to your back.

If you work in an office or school, summer is also the season of Cool Biz, Japan’s long-running campaign encouraging workplaces to adopt lighter clothing and sensible cooling practices. If your commute involves significant walking, keeping a spare shirt at work is one of those tiny decisions that makes you feel like the most organized person alive at approximately 8:27 a.m.

Hydrate Before You Become Desperately Thirsty

One tremendous advantage Japan has during summer is that drinks are available almost everywhere. Vending machines, convenience stores and supermarkets mean you are rarely far from water, tea or an electrolyte drink. Drink regularly rather than waiting until you are extremely thirsty, particularly when walking, exercising or working outdoors. The government’s WBGT guidance recommends increasingly frequent hydration and rest as the heat index rises.

For ordinary daily activity, water and other normal drinks are usually sufficient. During prolonged heavy sweating, electrolyte drinks such as Pocari Sweat or Aquarius can be convenient, and Japanese pharmacies and supermarkets also sell oral rehydration products. If you are heading somewhere rural, hiking, attending a festival or doing several hours of sightseeing, bring water with you rather than assuming the vending-machine gods will provide.

They usually will.

But heatstroke is an unnecessarily dramatic way to discover that the only machine nearby sells hot corn soup.

Rearrange Your Day Around the Heat

One of the most effective Japanese summer survival strategies costs nothing: stop insisting that every activity must happen in the middle of the afternoon.

If possible, do grocery shopping, exercise, gardening, long walks and outdoor sightseeing in the morning or evening. Summer evenings can remain uncomfortably warm, but removing the direct afternoon sun from the equation helps enormously.

Tourists are particularly vulnerable to the temptation to schedule temples, castles, shrines, parks and shopping streets continuously from 10 a.m. to 5 p.m. Build indoor stops into the itinerary instead. Museums, cafés, department stores, restaurants, libraries and shopping centers are not simply breaks from sightseeing; during extreme heat, they are part of a sensible heat-management plan.

Residents can apply exactly the same logic. If you need milk and it is 36°C outside at 2:00 p.m., perhaps the milk can wait.

Treat Your Commute Like a Small Expedition

A good summer commuting bag might contain water, a towel, sunscreen, a folding parasol, cooling wipes and a portable fan. Sunglasses and a spare shirt are excellent additions if you have space. If you walk or cycle to work, leave slightly earlier so you do not have to rush. Walking furiously because you are five minutes late generates additional body heat at precisely the moment when your body would prefer you not to.

Summer is the season for moving with the serenity of someone who has nowhere particularly urgent to be.

Sleeping Is Half the Battle

Nothing destroys your relationship with summer quite like lying awake at 2 a.m. discovering that the backs of your knees can sweat.

Japanese stores sell an entire ecosystem of 接触冷感 (sesshoku reikan), or cool-touch bedding: mattress pads, sheets, pillows, blankets and pillowcases. Some are more impressive than others, but breathable bedding and a thin summer blanket can make sleeping considerably easier.

Pair them with a fan or circulator, cooling pillow, cool shower before bed and AC or portable cooling where available. If you do have an AC, you do not have to switch it off simply because you are going to sleep; indoor heat illness is a real risk, particularly when nighttime temperatures remain high.

Know the Signs of Heat Illness

At some point, “I am hot and miserable” can become “I need medical attention,” and knowing the difference matters.

Heat illness can include dizziness, excessive sweating, headache, nausea, muscle cramps, weakness, confusion and eventually loss of consciousness. If someone begins showing symptoms, move them somewhere cool, loosen unnecessary clothing and actively cool their body. If they are alert and able to drink safely, give them fluids. If someone becomes confused, collapses, loses consciousness or cannot drink independently, treat the situation as an emergency rather than attempting to fix it with another bottle of Pocari Sweat.

Japan’s emergency number for an ambulance is 119.

The Secret Is Not Trying to Win Against Summer

There can be a temptation, especially during your first year in Japan, to treat summer as something you should eventually become tough enough to ignore.

You probably will acclimatize somewhat, and eventually you may stop announcing “IT’S SO HUMID” every morning as though the nation has not noticed. But also maybe not, if you’re anything like me. People in Japan are not surviving August through superior moral character. They are carrying parasols, hiding from the afternoon sun, drinking from vending machines, wearing breathable clothing, covering their windows, running air conditioners, and purchasing bizarre refrigerated accessories for their necks.

Do the same. Japanese summer becomes substantially easier once you stop trying to conduct your life exactly as you would in October.

Check the WBGT. Carry water. Walk slowly. Block the sun before it enters your apartment. Use the air conditioner if you have one, and investigate window or portable units if you do not.

And when all else fails, there is always kakigori.