What do people get wrong about packing for summer in Japan?

This answer is a draft. It stays unpublished until legal review and source verification are complete.

Visitors pack for heat. What catches most of them out is the humidity that comes with it — and the fact that 2025 was the worst summer on record for heat-related ambulance calls.

The numbers behind the advice

The Fire and Disaster Management Agency reported 100,510 people taken to hospital by ambulance for heat illness between May and September 2025 — the first time above 100,000 since records began in 2008. June alone saw 17,229 cases, a monthly record. 57.1% of patients were aged 65 or over, and the most common location was the home (38.1%), not outdoors.

[Verify] Figures from FDMA's 2025 heat-illness statistics. Confirm before publication.

Misunderstanding 1｜Less clothing is the answer

At high humidity sweat evaporates slowly. Thin, loose, breathable fabric works better than less fabric. Cover can be cooler than exposure in strong sun.

Misunderstanding 2｜Indoors will be a relief

Air conditioning can be strong on trains and in shops. A light layer you can put on indoors is genuinely useful.

Misunderstanding 3｜One pair of shoes is enough

Shoes take a long time to dry in humid weather, and sudden rain is common. A second pair saves a day.

Misunderstanding 4｜Sun protection is only for the beach

UV levels can be high in cities. Japanese sunscreens carry a PA rating (PA+ to PA++++) for UVA alongside SPF. Check the product's instructions for amount and reapplication.

Misunderstanding 5｜Heat illness happens to other people

38.1% of cases happened at home. Drink regularly, use air conditioning, and if you feel dizzy, nauseous or stop sweating, move somewhere cool and seek medical help.

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Sources

• Fire and Disaster Management Agency — heat illness information (ambulance transport statistics)

https://www.fdma.go.jp/disaster/heatstroke/

• Ministry of the Environment — heat illness prevention information site

https://www.wbgt.env.go.jp/

• Japan Meteorological Agency — UV information

https://www.data.jma.go.jp/gmd/env/uvhp/

⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.

About this article

What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.

This is general information. Results vary from person to person and depend on your own conditions and surroundings.

Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.

This article is not intended to diagnose, treat, or prevent any condition. If you feel unwell, please consult a healthcare professional. Rules and procedures can change.

Sources

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