Japan is joining much of Southeast Asia in grappling with the effects of El Niño, with weather officials warning that above-average temperatures are likely to persist through October as the country experiences increasingly intense summer heat.
In Tokyo, the mercury exceeded 35°C within hours of the Japan Meteorological Agency declaring the rainy season over in the Kanto and Tokai regions on 20 July.
Authorities have since issued heatstroke alerts across much of the country, from Tohoku in the north to Kyushu in the south.
Officials expect August to be the hottest month, with eastern and western Japan likely to experience frequent days above 35°C. While September is not expected to reach last year's record-breaking extremes, forecasters say the heat will linger well into autumn, with October temperatures also forecast to remain normal or above normal nationwide.
The JMA also warned that warmer-than-average surrounding sea temperatures could mean that typhoons approach Japan with significant impact.
'Cruelly hot' days become the new reality
The extreme conditions have prompted Japan to introduce a new weather classification this year: kokushobi, or "cruelly hot day", for temperatures reaching 40°C or higher.
Since its introduction in April, several cities in central Japan, including including in the Aichi and Gifu regions have exceeded this threshold. More recently, the country recorded five consecutive kokushobi days – the longest streak since records began in 2010.
The impact is already being felt. Nearly 11,000 people required emergency medical treatment for heat-related illnesses in a single week between 13 and 19 July. Across the same time frame last year, 10,000 were hospitalised for heat-related illnesses in Japan.
Japan records around 1,300 heat-related deaths annually and has set a target of halving that number by 2030.
What travellers should know
For travel advisors, the prolonged heat means clients should prepare for conditions that may be significantly hotter than expected.
Travellers are encouraged to:
Stay well hydrated with water and electrolyte drinks throughout the day.
Schedule outdoor sightseeing for early mornings or evenings where possible where it is cooler.
Take regular breaks in air-conditioned shopping centres, museums or cafés.
Wear lightweight, breathable clothing, hats and sunscreen.
Monitor local heatstroke alerts issued by the Japan Meteorological Agency.
Recognise the early signs of heatstroke, including dizziness, headache, nausea, confusion and unusual fatigue, and seek medical attention immediately if symptoms worsen.