59 farm heat deaths push Japan's aging workforce to night shifts

For health professionals, Japan's farming crisis is a case study in occupational heat illness among an aging workforce. With 70% of farmers over 65 and a record 59 heat-related deaths in 2024 — more than double 2021 — heat stress is now a leading workplace safety issue in the sector. Nearly 60% of younger farmers report having suffered heatstroke or knowing someone who did, signaling an under-measured burden that wearable monitoring and wet-bulb temperature alerts could help quantify and prevent.

Japan's agricultural sector is undergoing a fundamental restructuring of its working day as farmers abandon midday schedules to survive lethal summer heat. In Nikko, Tochigi Prefecture, 36-year-old flower farmer Motoaki Iijima now harvests pink and orange gerberas under halogen lights long after sunset, having concluded that the daytime sun has become a mortal threat rather than a routine working condition. His transformation began three summers ago, when a part-time worker collapsed from heatstroke while picking sunflowers inside his greenhouse — an incident that pushed him to convert his operation to a nocturnal schedule, working outdoors through the night and stopping only when the morning sun turns punishing again. The hours around dusk, he says, have become precious.

“

A Japan Weather Association survey last year found that about 60% of farmers aged 20 to 50 had either personally suffered heatstroke or knew someone who had, while nearly 60% had already shifted their working hours earlier or later in the day.

Iijima is not an outlier. Reporting from The Asahi Shimbun and AsiaOne, drawing on Reuters material, describes farmers across Japan — from flower and asparagus growers to egg producers — rewriting the agrarian clock, with once-busy midday hours now treated as dangerous. The pattern is global: rice farmers in Vietnam and winery workers in Spain are similarly shifting labor to cooler nighttime and early-morning windows to beat more frequent and intense heatwaves. But Japan's exposure is unusually acute. Around 70% of the country's farmers are 65 or older, a demographic with reduced thermoregulatory capacity and elevated vulnerability to heat stress, and the nation's high humidity amplifies the danger by impairing the body's evaporative cooling. When outside temperatures top 35°C (95°F), now increasingly common in the region, greenhouse interiors can exceed 40°C.

The human cost is already measurable and escalating. A record 59 agricultural workers died from extreme heat in Japan in 2024, more than double the death toll recorded in 2021. A Japan Weather Association survey last year found that about 60% of farmers aged 20 to 50 had either personally suffered heatstroke or knew someone who had, while nearly 60% had already shifted their working hours earlier or later in the day. These figures indicate that nocturnal work is not a speculative trend but an already-widespread, grassroots adaptation spreading through the sector.