Japan rainfall warnings: Vehicle flooding risks and safety advice

Heavy rainfall and sudden guerrilla rainstorms have increased the risk of road flooding and vehicle damage. In Chiba Prefecture, record-breaking rainfall between August 13 and 14, 2026, resulted in over 3,000 vehicles becoming stranded on public roads due to flooding.

Safety tests conducted by JAF indicate that even large SUVs are not immune to deep water. While some SUVs can navigate water depths of 30cm, a depth of 60cm can cause engines to stall, even at low speeds. Experts warn that once water reaches the bottom of a car door, the external pressure makes it extremely difficult to open, and rising levels can trap occupants.

Drivers are advised to avoid entering flooded roads entirely if the depth or road conditions cannot be clearly verified. Relying on the ability of a preceding vehicle to pass is dangerous, as intake heights and ground clearances vary by model. Additionally, submerged hazards such as open manholes, debris, and fallen trees may be hidden beneath murky water.