Tokyo logged its first day of extreme heat this year on 7 July, with the temperature climbing to 35.6 °C shortly before noon—three days later than in 2024. The reading marked the capital’s inaugural ‘moshobi’, the Japan Meteorological Agency’s term for days when the mercury tops 35 °C, and signalled the start of a wider heatwave across the archipelago. The Fire and Disaster Management Agency said 10,048 people were taken to hospital with suspected heatstroke in the week through 6 July, the highest weekly total since monitoring began on 1 May and more than twice the figure a week earlier. At least 54 of the latest cases occurred in Tokyo on 9 July, when more than 130 observation sites nationwide also recorded temperatures of 35 °C or higher. Authorities have issued successive heat alerts, advising residents to stay hydrated, use air-conditioned facilities and check on vulnerable neighbours. Local governments are opening cooling centres and dispatching water-spraying vehicles to lower street-level temperatures, while medical services remain on heightened standby. Similar conditions are being reported elsewhere. In South Korea, emergency departments have treated over 1,200 people for heat-related illnesses since mid-May after temperatures in Gyeonggi Province briefly reached 40.2 °C—an early-July record—and at least seven deaths have been confirmed. In the United States, the Maryland Department of Health has attributed 11 fatalities to the heat so far this summer. The parallel spikes underscore mounting health risks as prolonged high temperatures grip parts of the Northern Hemisphere.