In mid-August, Japan usually celebrates Obon, a holiday for visiting family. However, on August 13, 2026, heavy rain caused severe flooding in Chiba prefecture. Thousands of travelers were stranded at Narita International Airport in Chiba because roads and train lines were underwater. Airport staff provided food, drinks, and beds for the trapped passengers.
The storm formed when warm, moist air met cold air, creating unstable weather. The Japan Meteorological Agency issued its highest alert for heavy rain in Chiba. In one hour, Chiba city received 115 millimeters of rain, which is usually the amount for the whole month of August. Some areas received over 360 millimeters in 24 hours.
The rising water became dangerous, and at least four people died. One victim was a woman in her car, and another was a man found in floodwaters. Emergency services worked to rescue people in the flooded areas.
Officials ordered over 400,000 people in Chiba and Ibaraki prefectures to leave their homes. The storm caused power outages for many households. The weather agency also warned about possible landslides.
Over 200 shelters were opened for people who lost their homes. The military was called in to help with rescues, saving about 4,000 people stuck at Soga railway station. By Friday morning, the rain lessened, and Narita Airport planned to resume normal flight operations. The governor of Chiba described the event as extremely unusual, even for Japan.