If you’re planning to visit Japan during the summer months—especially between late June and early September—you may be in for a surprise. Japan’s summer heat isn’t just about high temperatures. It’s the relentless humidity that makes it almost unbearable for many travelers and residents alike.
In 2025, major cities like Tokyo, Osaka, and Fukuoka are already experiencing heat indices above 40°C (104°F) even before the official end of the rainy season (梅雨). This unique combination of heat, humidity, and limited airflow can be dangerous if you’re not properly prepared.
1. Japan’s Summer Heat Is Different: The Humidity Trap
Unlike dry heat found in places like California or southern Europe, Japan’s summer comes with intense humidity, often exceeding 80%. Even if the thermometer shows 32°C (89°F), it can feel like 40°C (104°F) or more.
Example:
In Tokyo’s Shibuya Station, one of the world’s busiest stations, temperatures can reach 35°C inside the station corridors during rush hour. Without natural airflow and with crowds packed shoulder to shoulder, it’s easy to get dizzy or dehydrated within minutes.
2. Why Heatstroke Happens in Japan—Even Indoors
Heatstroke (熱中症 / necchūshō) is not just a risk outdoors. In Japan, many traditional homes and older buildings still lack central air conditioning. Elderly residents in particular are at risk—many refuse to use air conditioning to save electricity, leading to dangerous indoor temperatures.
Real case:
In 2023, over 70,000 people in Japan were taken to the hospital for heat-related illnesses during summer, and more than 1,000 deaths were attributed to heatstroke, with many victims being over the age of 65.
3. Practical Tips for Avoiding Heatstroke in Japan
Here are some proven ways to survive the Japanese summer:
✅ Stay Hydrated (but not just with water)
Drink sports drinks like Pocari Sweat or Aquarius that replenish salts and minerals. Plain water is important, but you also need electrolytes.
✅ Avoid Midday Outdoor Activities
Between 11:00 a.m. and 3:00 p.m. is the peak heat time. If sightseeing, plan indoor visits (museums, shopping malls, temples with shaded areas) during these hours.
✅ Use Cooling Products
Japan sells excellent heat protection goods at convenience stores and drugstores:
- Cooling sprays
- Gel packs for your neck
- Cooling towels (冷感タオル)
- UV umbrellas (日傘), even for men!
✅ Dress Smart
Wear light, breathable fabrics. Many locals wear UNIQLO AIRism clothing during summer. Also, avoid dark colors which absorb heat.
✅ Recognize the Early Signs of Heatstroke
- Dizziness
- Nausea
- Headache
- Confusion
- Lack of sweating (in later stages)
If any of these occur, seek shade, cool down with water or air conditioning, and get medical help if necessary.
4. Public Facilities for Emergency Cooling
If you’re out and about and feel unwell, look for these spots:
- Convenience stores (コンビニ) – Always air-conditioned and welcome to rest inside.
- Public libraries or community centers – Free to enter and usually very cool.
- Department stores – Spacious, air-conditioned, and have free seating areas.
In large cities, many municipalities also open “Cooling Shelters” (クーリングシェルター) on extreme heat days.
5. What Tourists Often Underestimate
Many foreign visitors assume summer in Japan is just “warm and sunny.” In reality, it can be physically exhausting, even for locals. Long walks through temples, crowded train rides, and long queues at amusement parks like Disneyland can all be heat traps.
Real Experience:
A Canadian tourist in Kyoto collapsed while waiting in line at Fushimi Inari Shrine in August 2024. He later told NHK, “I thought I was just sweating too much. I didn’t realize I was actually in danger.”
Conclusion: Take Japan’s Summer Seriously
Japan in summer is beautiful—think fireworks festivals, shaved ice (かき氷), and vibrant matsuri—but the climate is unforgiving. Especially if you’re not used to extreme humidity, it’s essential to plan ahead, take frequent breaks, and prioritize your health.