If you’re visiting Japan between June and September, you’ll notice something quickly that it’s very hot. And not just hot, but 湿気がすごい (very humid). Many travelers are surprised at how intense the heat feels, especially in places like Tokyo, Kyoto, and Nagoya. Also with many people around, it feels like the heat and humidity multiplies. Every year, thousands of people across Japan suffer from necchuusho (熱中症), or heatstroke.
It’s something you need to take seriously while exploring the country. This guide will help you stay safe, cool, and hydrated so your summer trip stays fun, and not cut short by a hospital visit.
What is Necchuusho?
Necchuusho is the Japanese word for heatstroke or heat-related illness. It happens when your body can’t regulate its temperature due to high heat, humidity, and dehydration.
Unlike regular fatigue or sweating, necchuusho can come on suddenly and get dangerous very quickly. If untreated, it can lead to unconsciousness, organ failure, or worse.
Japanese weather services even issue heatstroke warnings in the summer. When you see the term 「熱中症警戒アラート」 (necchuusho keikai alert), it means conditions are especially risky.
When Does It Happen?
Necchuusho is most common between late June and early September, especially during the 梅雨 (tsuyu) rainy season and the high heat of July and August. Humidity often reaches 70–90%, and cities like Kyoto can feel like a sauna.
The danger zone is typically from 11:00 AM to 3:00 PM, but in some places it stays hot even at night.
Tip: Many locals avoid going outside in the early afternoon unless necessary. You’ll see more people out in the mornings and evenings.
Symptoms to Watch Out For
Heatstroke doesn’t always start with fainting. It often begins with more subtle symptoms. Watch for:
- Feeling dizzy or light-headed
- Headache
- Nausea or upset stomach
- Muscle cramps
- Excessive sweating (or suddenly stopping sweating)
- Red, hot skin
- Rapid pulse
- Confusion or slurred speech
- Fainting or losing consciousness
If you feel “off,” don’t brush it off. Rest, hydrate, and cool down immediately.
How to Prevent Necchuusho While Traveling
Here are practical ways to stay safe during your Japan adventure:
1. Hydrate Often
Drink water regularly even if you’re not thirsty. Japanese convenience stores sell bottle of water and スポーツドリンク (sports drinks) like Pocari Sweat and Aquarius, which replace lost electrolytes. Try to keep a bottle in your bag at all times.
2. Dress Smart
Wear light-colored, loose, breathable clothing. Hats and parasols are common in Japan (especially among locals), and many tourists find them helpful.
In summer, even the salarymen loosen their ties and switch to short sleeves.
3. Use Cooling Goods
You’ll see cooling goods and gadgets everywhere in summer such as cooling sheets, neck fans, UV arm covers, even wearable ice packs. Places like Don Quijote, Loft, and Daiso sell them cheaply. In theme parks such as Tokyo Disneyland, Tokyo DisneySea and Universal Studios Japan, they have character themed portable fans and other cooling gadgets.
4. Plan Around the Heat
Schedule your sightseeing early in the morning or later in the evening. Avoid long outdoor walks in the early afternoon. Temples, shrines, and parks often have shaded rest areas or vending machines nearby.
5. Take Breaks Indoors
Convenience stores, department stores, and cafes are air-conditioned. Use them to cool off when needed. Japan is super welcoming of short stops, even if you just buy a drink.
What To Do If You or Someone Else Has Necchuusho
Don’t wait. If someone is showing symptoms, act fast.
- Move to a cool, shaded, or air-conditioned spot
- Loosen clothing and lay them down
- Use a wet towel or fan to cool the body
- Offer water or a sports drink if they’re conscious
- If they faint, vomit, or seem confused, call 119 (Japan’s emergency number)
Japanese phrase to show someone:
「熱中症かもしれません。助けてください。」
(Necchuusho kamo shiremasen. Tasukete kudasai.)
Meaning: They might have heatstroke. Please help.
Emergency responders in Japan are very professional and used to helping tourists.
Who is Most at Risk?
Even healthy adults can get necchuusho, but it’s especially risky for:
- Children and babies
- Older travelers
- People with preexisting conditions
- Tourists not used to humid climates
- Anyone walking long distances, especially with luggage
- People wearing masks in extreme heat (still common in Japan)
Real Stats: Why You Should Care
In 2023 alone, over 70,000 people in Japan were hospitalized for heatstroke. Many of those were during outdoor activities or just walking around cities like Tokyo and Osaka.
Local governments now provide real-time heat alerts and guidelines. You can check updates here:
https://www.wbgt.env.go.jp/en/ (English)
What You Should Pack for Summer in Japan
If you’re coming during the hot months, don’t forget these:
- Reusable water bottle
- Sports drinks or salt tablets
- Cooling towels or neck wraps
- Sunblock and hat
- Light clothing
- Small portable fan or hand towel
- Heatstroke emergency card (in Japanese/English) if you have a health condition
Don’t let the heat stop you from enjoying Japan. Just be prepared, listen to your body, and take it slow.
