A powerful typhoon is moving toward Japan’s eastern Pacific coast, placing Tokyo and surrounding areas on high alert as intense rainfall, violent winds, flooding and landslides threaten communities across the Kanto region.

Typhoon Dujuan, the 25th typhoon of the year, was approaching eastern Japan on Monday, with the Japan Meteorological Agency warning that weather conditions could deteriorate rapidly as the system moves closer to the Tokyo metropolitan area.

The immediate concern is not only the strength of the storm but also the amount of rain that has already fallen across parts of eastern Japan. Some locations in the Izu Islands and Chiba Prefecture have received more than 300 millimetres of rain since Saturday, leaving soils saturated and increasing the possibility that additional rainfall could trigger flash floods and landslides.

Heavy Rain Could Become the Biggest Threat

Forecasts indicate that the heaviest rainfall could occur as Dujuan approaches the Kanto and surrounding regions. The weather agency has warned that rainfall totals during a 24-hour period could reach around 350 millimetres in parts of the Tokai region, 300 millimetres in Kanto and the Izu Islands, and 200 millimetres in Tohoku.

Such rainfall becomes particularly dangerous when it falls over ground that has already absorbed large amounts of water.

One of the major concerns is the possible development of linear rainbands. These narrow but persistent bands of thunderstorms can remain over approximately the same location for several hours, producing extraordinary amounts of rain within a relatively small geographical area.

That means the overall storm track does not necessarily determine where the most serious flooding will occur. A comparatively small area can receive exceptionally intense rainfall while nearby locations experience considerably less.

Tokyo Region Faces Multiple Weather Hazards

The Kanto region, which includes Tokyo and several densely populated surrounding prefectures, faces a combination of hazards.

Heavy rainfall can rapidly overwhelm drainage systems in urban areas. Water can accumulate on roads, enter underground facilities and cause rivers and smaller waterways to rise quickly.

At the same time, saturated slopes become increasingly vulnerable to landslides. This creates a particularly complicated emergency situation because flooding and landslides can occur simultaneously, potentially cutting off roads and restricting access for emergency services.

Authorities have therefore urged residents in vulnerable locations to remain alert rather than relying only on the storm’s exact centreline.

Transport Disruptions Spread Across Eastern Japan

The typhoon is also affecting transportation during Japan’s extended holiday period.

Parts of highways have already been closed, while railway operators have warned of suspensions, delays and cancellations in several areas. Bullet train services connecting Tokyo and Osaka could also face disruption as the storm moves closer.

The consequences extend beyond ordinary commuting. Japan is experiencing a busy holiday period, meaning large numbers of people are travelling at a time when severe weather is approaching.

Transport interruptions can therefore have a cascading effect, leaving travellers stranded, forcing changes to accommodation plans and complicating movement between affected communities.

Major Events Also Feeling the Impact

The approaching storm has affected sporting and cultural activities.

At the Asian Games being held in Aichi Prefecture, the equestrian eventing competition was postponed because of the deteriorating weather conditions.

The Tokyo Game Show also cancelled its planned final-day programme as the typhoon approached.

These disruptions illustrate how powerful weather systems can affect more than emergency management. Large sporting events, exhibitions, tourism, entertainment and local businesses can all be forced to adjust their operations when extreme weather creates safety and transportation concerns.

Why the Situation Deserves Attention Beyond One Storm

Typhoon Dujuan is a weather event, but its wider significance lies in the growing challenge of managing extreme rainfall in highly populated areas.

Climate change does not mean that every individual typhoon can automatically be attributed to global warming. Establishing such a connection requires detailed scientific analysis of the particular storm, its atmospheric environment and long-term climate patterns.

However, a warmer atmosphere can hold more moisture, creating the potential for heavier rainfall when suitable weather systems develop. This is one reason why scientists and disaster-management authorities pay close attention to extreme precipitation as the climate continues to warm.

For Japan, this issue is particularly important because the country already has extensive experience dealing with typhoons, steep terrain, rivers and concentrated urban populations.

Saturated Ground Could Increase the Danger

Another important factor is the sequence of rainfall.

If extremely heavy rain falls on relatively dry ground, some of the water can initially infiltrate into the soil. But when repeated rainfall saturates the ground, the capacity to absorb additional water becomes much smaller.

This can increase surface runoff and accelerate the rise of rivers and streams.

In mountainous and hilly areas, saturated soil can also become unstable. A landslide may occur suddenly, sometimes with little warning, making rainfall intensity and duration critical factors in assessing risk.

This explains why authorities are particularly concerned about areas that have already received substantial rainfall before Dujuan’s closest approach.

Urban Areas Present a Different Challenge

Tokyo and surrounding cities face a different set of vulnerabilities.

Dense development means that large portions of the ground are covered by buildings, roads and other impermeable surfaces. During extremely heavy rainfall, water cannot easily penetrate the ground and can instead move rapidly through streets and drainage networks.

Underground spaces are another concern.

Subways, underground shopping areas, tunnels and basement facilities can become dangerous if floodwater enters quickly. Even relatively shallow flooding can create serious problems for vehicles and pedestrians.

As a result, severe-weather preparedness in major cities increasingly depends on rapid warnings, drainage capacity, transportation management and public cooperation.

What Happens Next

The immediate focus remains on the storm’s movement past eastern Japan and the evolution of rainfall across Kanto, Tokai, the Izu Islands and parts of Tohoku.

The most important risks are expected to come from a combination of torrential rain, strong winds, high waves, river flooding and landslides.

Residents in vulnerable areas are being urged to follow official weather and evacuation information and avoid unnecessary travel during the most dangerous period.

For emergency planners, the challenge will be determining where rainfall becomes concentrated and how quickly rivers, drainage systems and unstable slopes respond.

Typhoon Dujuan therefore represents more than a single episode of bad weather. It is a test of Japan’s ability to manage compound hazards in a densely populated and highly connected region, where heavy rainfall can simultaneously affect public safety, transportation, tourism, infrastructure and major events.