Key Facts
• June 2025 experienced an unprecedented early heatwave across Japan.
• Rice field water temperatures reached 40.5°C, exceeding the optimal 25–30°C range.
• Farmers in Nara reported weakened rice seedlings due to heat and water shortages.
• Invasive species like the golden apple snail exacerbated crop damage.
• Osaka researchers observed algae overgrowth suffocating rice plants.
• High temperatures in 2010 and 2023 caused rice quality to drop to 60% first-grade.
• Experts warn continued heat and drought may reduce rice yield and quality.
• Rising temperatures hinder starch accumulation, leading to immature grains.
• Concerns grow over potential price hikes and reduced availability of new rice.
• Farmers and researchers fear a repeat of the 2023 “Reiwa Rice Crisis.”
Summary
An early heatwave in June 2025 has caused severe disruptions in Japan’s rice production. Water temperatures in rice fields have soared to 40.5°C, far above the ideal range, leading to weakened seedlings and increased vulnerability to invasive species like the golden apple snail. Algae overgrowth, driven by high temperatures, has further suffocated rice plants. Experts warn that prolonged heat and drought could significantly reduce both the yield and quality of rice, with immature grains becoming more common. Historical data from 2010 and 2023 shows similar heatwaves led to a drop in first-grade rice quality to 60%, sparking fears of another “Reiwa Rice Crisis.” Farmers and researchers are deeply concerned about the potential for price hikes and reduced availability of this year’s new rice.
