Japan Meteorological Agency Chief Ryuichi Nomura said Wednesday that the late rainy season poses the highest risk of heavy rain across the country.

This warning comes as the region enters a volatile weather window where past precipitation has frequently caused catastrophic disasters. Officials said that even shallow flooding can impede movement, making early action critical for survival.

Nomura said that the rainy season front will be fully active for approximately one month [1]. He said residents should closely monitor new disaster weather information and municipal evacuation notices to ensure timely departures from high-risk areas.

The agency said the danger of knee-depth flooding [2] can make evacuation physically difficult or impossible. Because of this risk, the JMA is promoting a tiered warning system to clarify the necessary response for different demographics.

Nomura addressed the use of Level 3 and Level 4 alerts to guide public behavior. He said, "Level 4 emergency warnings have made it easier to understand the actions to be taken when heavy rain actually occurs; for the elderly and others, I hope they will take firm action to protect their lives based on Level 3 warnings and evacuation information issued by municipalities" [3].

The JMA said that Level 3 and Level 4 warnings are likely to be issued as the weather patterns shift [3]. Residents are advised to identify their local evacuation routes, and shelters, before the heaviest rains arrive this month.

“The late rainy season poses the highest risk of heavy rain across the country.”

The JMA's emphasis on the 'late rainy season' reflects a strategic shift toward preemptive evacuation. By highlighting the danger of knee-depth water, the agency is attempting to combat the 'normalization bias' where residents underestimate the difficulty of wading through floodwaters. The focus on Level 3 and 4 warnings indicates a push for a more granular, tiered response system to reduce casualties among vulnerable populations, such as the elderly, who cannot wait for a Level 4 emergency to move.