Tokyo’s skies displayed a rare atmospheric phenomenon today as a “halo” encircled the sun over the city center, while meteorologists warn of unstable conditions that could trigger sudden, heavy downpours across the Kanto region—including Tokyo—this afternoon.
The halo, characterized by white or rainbow-colored rings around the sun, appeared in Tokyo’s urban skies today, June 13, under overcast conditions. Similar atmospheric conditions may allow the phenomenon to be visible in other parts of Kanto, though observers are advised to avoid direct sunlight when viewing it.
Why is a halo forming over Tokyo—and what does it mean for the weather?
A halo occurs when ice crystals in high-altitude cirrus clouds refract sunlight, creating the ring effect. While visually striking, its presence often signals unstable atmospheric conditions—exactly what Kanto is experiencing. According to meteorological forecasts, the region’s upper atmosphere (around 5,500 meters) has seen unusually cold air for this time of year, with temperatures dropping below -15°C. Combined with lingering humidity and daytime heating, this instability is expected to persist into the evening.
Did You Know? Halos are most commonly observed in winter, but their appearance in early summer—like today—can indicate a sharp contrast between warm surface temperatures and cold upper-level air, a pattern that often precedes sudden weather shifts.
What could happen next? Kanto’s risk of sudden, severe thunderstorms
Kanto already faced localized thunderstorms yesterday, June 12, and today’s conditions may bring similar disruptions. Meteorologists warn that the region could see heavy rain with lightning—particularly between late afternoon and early evening—as the cold air mass interacts with moist, warming surface air. Key risks include:
- Flash flooding in low-lying areas, including underground streets and riverbanks.
- Roadway flooding, with potential for water to rise quickly in urban drainage systems.
- Strong winds, including possible downbursts or localized tornadoes.
Expert Insight: The combination of high humidity, unstable air, and urban heat islands in Tokyo and surrounding cities could intensify localized downpours. Historical data shows that Kanto’s thunderstorm season peaks in early summer, with June often seeing the highest frequency of sudden, high-intensity rain events. Residents should prepare for rapid changes in weather, as forecasts may not capture the exact timing or severity of localized storms.
How to stay safe during sudden heavy rain in urban areas
When flash flooding strikes in cities, water can accumulate unexpectedly—even in areas not typically prone to flooding. Authorities recommend three key precautions:
- Seek shelter above ground level: Avoid basements, underground malls, or bridges (where rising water poses drowning risks). Opt for the first floor or higher of buildings.
- Never walk through flooded roads: Just six inches of moving water can knock a person off their feet, while deeper water may conceal hazards like open manholes. If crossing is unavoidable, use a stick to test footing.
- Drive with caution around low-lying roads: Cars can become trapped in floodwaters, and doors may jam shut due to water pressure. Highways with underpasses are particularly risky.
Frequently Asked Questions
[Can a halo predict the weather?]
While halos themselves don’t forecast specific conditions, their presence often coincides with high-altitude ice crystals—typically found in unstable air masses. Today’s halo aligns with meteorological data showing cold upper-level air interacting with warm, moist surface air, increasing the likelihood of thunderstorms.
[Is Tokyo at risk of tornadoes during these storms?]
Localized tornadoes or strong wind gusts are possible, particularly in areas where cold air clashes with warm, humid air near the ground. While rare, Kanto has seen brief tornadoes during summer thunderstorms, so residents should monitor alerts for sudden wind shifts.
[How long might the unstable weather last?]
Current forecasts suggest the cold air mass will linger through June 13, with the highest risk of thunderstorms occurring between late afternoon and evening. However, if the system stalls, additional instability could persist into June 14.
With sudden weather shifts possible, how are you preparing for potential disruptions in your area?
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