Japan's Rainy Season Officially Ends Nationwide: JMA Declares End of Tsuyu in Hokuriku and Tohoku

Published: August 4, 2026 | Rail News Bulletin | japantrain.net

The Japan Meteorological Agency (JMA) announced on the morning of August 4, 2026, that the rainy season has likely ended in the Hokuriku region, Southern Tohoku, and Northern Tohoku — marking the official conclusion of tsuyu across all regions of Japan. With the end of the rainy season comes a sharp and dangerous shift to extreme heat. Fukuoka Prefecture is forecast to reach 39°C, and areas still recovering from the Kumamoto earthquake are also expected to face severe temperatures. The JMA is urging all residents and travelers to take thorough heatstroke prevention measures. For rail passengers across Japan, this weather transition carries practical implications for journey planning, platform comfort, and onboard conditions.

What Happened: JMA Declares End of Rainy Season in All Regions

On the morning of August 4, 2026 (Japan Standard Time), the Japan Meteorological Agency officially announced that the regions of Hokuriku, Southern Tohoku (Tohoku South), and Northern Tohoku (Tohoku North) have likely exited the rainy season, known in Japanese as tsuyu (梅雨). According to the JMA's assessment, these were the final regions still experiencing the seasonal rain front's influence.

With this announcement, all regions across Japan have now officially exited the 2026 rainy season. This includes the regions that had already been declared clear of tsuyu in prior weeks — such as Okinawa, Kyushu, Shikoku, Kanto-Koshin, Tokai, and Kinki. The Hokuriku and Tohoku regions had been the last holdouts, and their declaration completes the nationwide transition into full summer conditions.

Key Facts From the Announcement

• Date of announcement: August 4, 2026, morning (JST)
• Issuing body: Japan Meteorological Agency (気象庁)
• Regions declared clear: Hokuriku, Southern Tohoku, Northern Tohoku
• Nationwide status: All regions have now ended their rainy season
• Primary concern: Extreme heat and heatstroke risks immediately following the end of tsuyu

The JMA's phrasing — that the regions are "considered to have likely ended the rainy season" (梅雨明けしたとみられる) — reflects the agency's standard meteorological methodology. Tsuyu endings are determined through analysis of weather patterns, precipitation trends, and atmospheric conditions rather than a single definitive event.

Heat Advisories: Dangerous Temperatures Expected Across Japan

While the end of the rainy season is a recognized annual milestone, the JMA used this announcement as an opportunity to issue a strong warning about heatstroke risks. The agency highlighted two areas of particular concern:

Fukuoka Prefecture: 39°C Forecast

Fukuoka Prefecture is forecast to experience temperatures reaching 39°C, which the source describes as "dangerous heat" (危険な暑さ). At this temperature level, the risk of heatstroke becomes extremely high for all individuals — regardless of age, fitness level, or acclimatization. The JMA classifies temperatures at and above this threshold as posing a serious health risk, particularly for outdoor activities and prolonged exposure.

Kumamoto Earthquake Disaster Area

Areas still recovering from the Kumamoto earthquake are also expected to face "extreme heat" (猛烈な暑さ). The source did not specify exact temperature figures for the Kumamoto disaster area, but the language used — 猛烈な暑さ — indicates conditions severe enough to warrant specific mention alongside the Fukuoka forecast. Residents and relief workers in temporary housing and affected zones face heightened vulnerability due to the ongoing recovery situation.

Nationwide Heat Context

While the JMA specifically highlighted Fukuoka and Kumamoto, the announcement's broader message applies to all of Japan. With the rainy season now ended nationwide, the transition into the peak of summer heat is expected to intensify across all regions. Travelers on major rail routes spanning from Hokkaido to Kyushu should be prepared for sustained high temperatures.

How This May Affect Rail Services Across Japan

It is important to note that the JMA announcement does not reference specific rail service disruptions. However, the end of the rainy season and the onset of extreme heat are historically significant factors for rail operations across Japan. Here is what rail travelers should be aware of:

Heat-Related Speed Restrictions

Japanese rail operators, including JR East, JR West, JR Kyushu, and private railways, regularly implement speed restrictions when rail track temperatures exceed safe thresholds. During periods of extreme heat — particularly when ambient temperatures reach the high 30s°C and above — tracks can expand and deform, creating safety risks. Speed restrictions are a preventive measure, and they can result in minor to moderate delays on affected lines.

The source announcement does not specify which lines or operators have implemented or may implement such restrictions. Travelers should check real-time service updates from their respective rail operators.

Platform and Station Conditions

Railway stations across Japan, particularly outdoor and elevated platforms, can become significantly hotter than surrounding areas during heatwaves. The combination of concrete surfaces, limited shade, and radiant heat from tracks creates conditions where perceived temperatures can exceed ambient air temperatures. Major stations in Fukuoka, such as Hakata Station, and stations throughout the Tohoku and Hokuriku regions may experience these elevated platform temperatures.

Onboard Air Conditioning

Modern Japanese trains are equipped with air conditioning systems that operate year-round. However, during extreme heat, carriages may feel warmer than usual when boarding, and systems may be strained during peak loads. The source did not provide specific information about air conditioning performance or capacity adjustments.

What Rail Travelers Should Do

The following advice is grounded in the JMA's announcement and supported by the source material. The JMA's core message is clear: take thorough heatstroke prevention measures (熱中症対策の徹底). Here is how this applies to rail travel:

Hydration

Carry sufficient water and electrolyte drinks for your journey. This applies to all segments of travel — including time spent on station platforms, transfers between lines, and walking to and from stations. The JMA's emphasis on heatstroke prevention underscores the importance of maintaining hydration levels throughout the day.

Timing Your Travel

If possible, consider adjusting your travel schedule to avoid the hottest parts of the day. Peak heat in Japan typically occurs between approximately 11:00 AM and 3:00 PM. Early morning and evening departures may offer more comfortable conditions, both on platforms and during transfers. This is general practical guidance consistent with the JMA's heatstroke prevention advisory.

Sun Protection on Platforms

Many Japanese rail stations — especially regional and suburban stations along local lines in Tohoku and Hokuriku — have outdoor or partially covered platforms. Use available shade, carry a portable fan or towel, and wear light, breathable clothing. Wide-brimmed hats and UV-protective accessories are advisable during platform waits.

Know Your Limits

The JMA's warning about heatstroke applies equally to travelers. If you experience dizziness, nausea, excessive sweating, or confusion while traveling, seek assistance immediately. Station staff at major and mid-sized stations are trained to respond to heat-related health incidents, and many stations have first-aid rooms. Do not attempt to push through symptoms.

Monitor Official Updates

The JMA's heat advisories are updated regularly. Check the latest forecasts before and during your journey. For rail-specific service information, consult the official websites and apps of your rail operator — including JR East (JR東日本), JR West (JR西日本), JR Kyushu, and relevant private railways. Real-time delay information is available through official operator channels and platforms such as the Japan Transit Planner.

Regional Context: Hokuriku and Tohoku Rail Travel After Tsuyu

The Hokuriku and Tohoku regions, now confirmed to have exited the rainy season, are home to several key rail corridors that serve both domestic and international travelers:

Hokuriku Region

• Hokuriku Shinkansen: Connecting Tokyo to Kanazawa via Nagano, this is a major high-speed rail corridor. Stations along the route — including Nagano, Toyama, and Kanazawa — will now transition into full summer heat conditions.
• IR Ishikawa Railway / Ainokaze Toyama Railway: Regional lines serving coastal areas of the Hokuriku region. Platform conditions at smaller stations may be particularly exposed.
• Hokuriku Shinkansen schedules and information

Tohoku Region

• Tohoku Shinkansen: The primary high-speed line connecting Tokyo to Shin-Aomori, serving major stops including Sendai, Morioka, and Shin-Hakodate-Hokuto (via Hokkaido Shinkansen connection). This corridor serves both Southern and Northern Tohoku.
• Akita Shinkansen and Yamagata Shinkansen: Mini-shinkansen services branching from the Tohoku Shinkansen at Morioka and Fukushima, respectively.
• Local and regional lines: Including JR East local services and third-sector railways that connect communities throughout the Tohoku region.
• Tohoku Shinkansen schedules and route information

The source announcement did not indicate any service disruptions, suspensions, or schedule changes on these or any other rail lines. The connection between the end of tsuyu and rail travel is one of environmental and safety awareness rather than a reported operational disruption.

Nationwide Heat Outlook: All Regions Now Post-Rainy Season

With the August 4 announcement, Japan's entire territory — from Okinawa in the south to Hokkaido in the north — has exited the 2026 rainy season. This marks the beginning of the country's hottest period. Historically, the weeks immediately following the end of tsuyu are among the most dangerous for heatstroke, as humidity levels remain high even as temperatures climb. The combination of residual moisture and rising heat creates a particularly hazardous environment.

For rail travelers, this means:

• Expect sustained high temperatures at stations, on platforms, and during outdoor transfers across all regions of Japan
• Heat-related speed restrictions may be implemented on various lines without extensive advance notice
• Crowding at stations during heatwaves can increase heat exposure — plan accordingly
• Regional lines in Kyushu (including Kyushu Shinkansen routes through Kumamoto), Tohoku, and Hokuriku may be particularly affected due to outdoor platform exposure

Official Source Information

Editor's note: We recommend consulting the original NHK source and the Japan Meteorological Agency official website for the most current and detailed weather advisories. Rail-specific service information should be obtained directly from the operating rail company.

Frequently Asked Questions

1. Has the rainy season ended across all of Japan in 2026?

Yes. According to the JMA's announcement on August 4, 2026, the Hokuriku, Southern Tohoku, and Northern Tohoku regions were the last to exit the rainy season. With their declaration, all regions of Japan have officially ended tsuyu for 2026.

2. Are there any rail service disruptions reported due to the heat?

The source announcement from NHK does not report any specific rail service disruptions. The JMA's advisory is a general heatstroke warning rather than an operational notice for rail services. However, travelers should be aware that extreme heat can lead to speed restrictions and minor delays on Japanese rail lines. Check with your rail operator for real-time service status.

3. What temperatures are expected after the end of the rainy season?

The source specifically mentions a forecast of 39°C in Fukuoka Prefecture and "extreme heat" (猛烈な暑さ) in the Kumamoto earthquake disaster area. The source did not provide specific temperature forecasts for other regions. The JMA's broader message is that heatstroke prevention measures should be taken nationwide.

4. Is it safe to travel by train during extreme heat in Japan?

Japanese rail operators take extensive safety measures during heatwaves, including speed restrictions and station staff monitoring. However, the JMA is advising all people to take thorough heatstroke prevention measures. Travelers should stay hydrated, seek shade on platforms, avoid travel during peak heat hours if possible, and be aware of heat-related symptoms. The source did not advise against rail travel.

5. How can I check for heat-related delays on my train route?

Rail operators publish real-time service updates through their official websites and mobile applications. For JR lines, check the respective JR company's service information page. For private railways, consult the operator's official channels. General delay information aggregators and transit planning apps also display current service status. Refer to our guide to Japan rail apps and tools for recommended resources.

This article is based on the NHK report published on August 4, 2026, and the Japan Meteorological Agency's official announcement. For the latest weather advisories, visit the JMA website. For rail service updates, consult your rail operator's official information channels. Last updated: August 4, 2026.