Japan’s summer (June–September) is intense. Tokyo regularly hits 35–38°C with humidity above 80%. Add the rainy season (tsuyu) before the heat peaks, and it’s one of the most challenging climates for newcomers.
The Japanese Summer Timeline
| Month | What’s Happening |
|---|---|
| June | Rainy season (梅雨, tsuyu) — grey, humid, daily rain |
| July | Rainy season ends; heat begins. Fireworks festivals start |
| August | Peak heat. Obon holiday. Outdoor festivals everywhere |
| September | Still hot until mid-month; typhoon season peaks |
Surviving the Heat: Practical Tips
Stay Hydrated
- Drink 1.5–2 liters of water per day minimum
- Convenience stores sell sports drinks (pocari sweat, aquarius) — better than water alone for electrolytes
- Avoid alcohol as your main hydration during extreme heat days
Cool Down Spots
- Convenience stores — everywhere, always air-conditioned
- Shopping malls and department stores — stay as long as you want
- Libraries, city halls — free, clean, air-conditioned
- Underground shopping streets — Tokyo, Osaka, and Nagoya have extensive underground networks
Clothing
- Lightweight, breathable fabrics (linen, moisture-wicking)
- Japanese “cool touch” (冷感) clothing — sold everywhere from ¥500 in summer
- Cooling towels — wet and wave for instant cooling, sold at ¥100 stores
- UV parasols — Japanese women (and increasingly men) carry these; extremely effective
Cooling Products from ¥100 Shops
- Cooling spray (冷却スプレー) — spray on skin for instant relief
- Cooling gel sheets (熱さまシート) — stick to forehead
- Mini portable fans with misting bottles — from ¥500 at convenience stores
- Ice neck rings — reusable PCM cooling rings
Heat Stroke (熱中症) Warning
Heat stroke is a genuine risk in Japan. Every summer, hundreds are hospitalized.
Warning signs:
- Dizziness, weakness, headache
- Stopping sweating despite heat
- Confusion or disorientation
What to do:
- Move to shade or air conditioning immediately
- Apply cold water/ice to neck, armpits, groin
- Call 119 if symptoms are severe
- Drink water or sports drink slowly
Prevention: Never exercise outdoors between 10am–4pm in July/August.
The Rainy Season (梅雨)
June is Japan’s rainy season — grey skies, daily rain, oppressive humidity.
Tips:
- Buy a portable umbrella — keep one in your bag at all times
- Coin laundry becomes essential — clothes don’t dry indoors
- Mold (カビ) grows fast — run a dehumidifier or air the apartment when possible
- Many great indoor activities: museums, cafes, onsen, indoor markets
Summer Events Worth Experiencing
- 花火大会 (Hanabi taikai) — fireworks festivals, July–August, hundreds across Japan
- 盆踊り (Bon Odori) — Obon festival dancing, August
- 夏祭り (Natsu matsuri) — summer festivals with food stalls and games
- 海水浴 (Kaisuiyoku) — beach swimming, popular in August
For festivals: wear a yukata (light summer kimono) — rental shops near major festivals.
Obon (お盆) — Mid-August Holiday
Japan effectively shuts down mid-August for Obon (roughly August 13–16).
- Trains and planes are packed and expensive
- Many restaurants and businesses close
- Traffic on highways is extreme
Plan ahead: Book travel or accommodation weeks in advance, or stay in your city and enjoy quieter streets.
Air Conditioning in Japan
Most Japanese apartments have AC (eakon — エアコン). Use it — don’t be heroic.
Tips:
- Set to 28°C — the government-recommended energy-saving temperature
- Use dry mode (除湿) in June for humidity — uses less electricity than cooling
- Direction matters — face vents upward so cold air falls naturally
- Use a timer so it switches off while you sleep
Electricity cost: Running AC constantly in August typically adds ¥5,000–10,000 to your electricity bill.