December–February
Winter: Sea of Japan coast
Cold continental air crossing the sea can create lightning-producing clouds along the Sea of Japan coast. JMA identifies this as a distinctive winter pattern, which may occur by day or night.
THE WEATHER, IN FOCUS
Japan thunderstorm radar.
Follow the clouds. Read the radar. Understand the storm.
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Interactive mapDrag to explore
Precipitation maps may include short-term forecasts. Check the time. This is not lightning detection.About these maps
Check the timestamp inside the map. A blank map does not mean there is no storm.
THE DAYS AHEAD
Japan: 7-day weather outlook.
A forecast for the selected place, not for all of Japan. Days and charts use UTC. Today may cover only the remaining hours.
Thunderstorm guidance is incomplete: a day without a thunder symbol is not an all-clear. Use official warnings for safety decisions.
The forecast loads as you reach this section.
How to use this forecast
Weather symbols describe model guidance for a point. “Thunder signal” means at least one displayed forecast interval contains a thunder symbol or a positive thunder probability. “No thunder symbol” is not an all-clear: lightning probabilities are not supplied for every location or every day, and small storms can be missed.
Rain totals add non-overlapping forecast periods. Temperature ranges include supplied interval extremes and available point samples; wind is the highest sampled sustained wind, not a gust forecast. Later days have coarser time steps and greater uncertainty. Check official warnings and radar again before outdoor plans.
Explore daily humidity, dew point, cloud cover and sea-level pressure. Gusts, apparent temperature, clear-sky UV and period probabilities appear only when supplied. Clear-sky UV assumes no clouds; it is not a forecast of actual UV exposure. A pressure change alone cannot establish whether a storm will develop.
Forecast data, attribution & licences · Forecast methods and limitations.
FIND YOUR VIEW
Explore nearby countries
THE YEAR AT A GLANCE
Thunderstorm seasons in Japan.
For thunderstorms in Japan, distinguish Japan's Sea of Japan coast, Pacific-facing slopes, mountainous interior and southern islands. These areas can have different moisture, temperatures and storm triggers on the same day.
Typical regional patterns, adapted to local geography. This is educational guidance, not a forecast for this year's seasons or a measured national lightning frequency.
December–FebruaryWinter: Sea of Japan coastMarch–MaySpring: regional transitionsJune–AugustSummer: widespread inland activitySeptember–NovemberAutumn: changing air masses
March–May
Spring: regional transitions
Warming inland terrain and passing fronts change the storm setup. Compare the Pacific side, Sea of Japan side and mountains; Japan’s long north–south extent makes one seasonal date inappropriate.
June–August
Summer: widespread inland activity
JMA’s lightning observations show a strong summer maximum across broad areas, with a clearer afternoon-to-evening peak. Inland heating and mountain terrain help explain why the local forecast can differ from the coast.
September–November
Autumn: changing air masses
Summer-style inland heating gradually weakens, while maritime disturbances and the transition towards cold-season coastal convection become relevant. Recheck the regional forecast rather than assuming all Japanese thunderstorms belong to summer.
What to watch in Japan
Include the surrounding ocean in the wider view, then compare satellite cloud bands with available precipitation observations. Offshore radar gaps need extra care.
Sources and scope · reviewed 25 September 2026
This country page combines the Japanese coastal winter and inland summer regional pattern with local geography. Timing shifts between years, elevations, islands and opposite sides of mountains. Rainy seasons do not automatically mean thunderstorms every day. The calendar is a reading aid, not a risk scale.
ZOOM OUT. FOLLOW THE LOOP. LOOK AHEAD.
What is heading towards Japan?
Include the surrounding ocean in the wider view, then compare satellite cloud bands with available precipitation observations. Offshore radar gaps need extra care. Use the map’s minus button to widen the view; plus brings you closer. A larger view gives context, not extra radar resolution.
- 01
Find the wider pattern
Zoom out until the approaching rain bands and nearby sea or land are visible. Check the timestamp and whether the frames are observations or model forecasts.
- 02
Follow several frames
Play the provider’s animation. Compare the same rain band over successive frames: is it approaching, weakening, growing or developing repeatedly over one area?
- 03
Check the airflow
Cloud-level winds help steer storms. The wind shown in the daily forecast is near the ground and can differ. Fronts, mountains and new cell development can change the direction.
- 04
Update your plans
Radar helps with the next short period. Use the 7-day outlook for broader planning and check local official warnings. A clear radar image does not prove lightning is absent.
This is a method for reading the map, not an automatic prediction of storm arrival. The country radar remains the opening view; Compare maps adds a draggable map.
Learn about storm movementASIA
Following storms
in Japan.
Which view should you use?
The page opens with rain radar to help you follow precipitation. Select Satellite for cloud imagery. These maps do not measure lightning strikes.
Check the area, not just the country name
The country view is a starting point. A large country or island territory may extend beyond the initial map. The country radar opens first. Choose Compare maps to add a second, draggable view alongside it (below it on smaller screens). Compare the timestamps and legends yourself; the maps are not synchronized and may share source data. Larger map expands the view. Missing data, especially away from radar stations, should not be interpreted as clear weather.
Find official weather warningsEXPLAINER · NOT LIVE WARNING STATUS
Japan: warning levels
JMA advisories and warnings
Japan distinguishes thunderstorm advisories from warnings for other storm-related hazards.
Thunderstorm advisory
Lightning precautions
Read the advisory and take shelter when thunder threatens.
Hazardous Wind Watch
Check wind information
A separate message concerns hazardous winds, including tornado-related threats.
Other hazard warnings
Follow the named hazard
Heavy rain, flood, landslide and storm-surge products have their own alert-level system.
JMA reorganised several hazard warnings in 2026. Do not interpret their five alert levels as five thunderstorm-intensity grades.
Sources and scope
Agency-specific warning explanation. Source review: 25 September 2026.
These are explanations, not active alerts. Always check the official area, issue time, expiry and instructions. Hearing thunder is a reason to take shelter at any warning level.
A LITTLE KNOWLEDGE GOES A LONG WAY
Understand the storm.
STORM SAFETY
Stay safe in a thunderstorm
Practical lightning safety: choosing shelter, avoiding exposure and knowing when to go outside again.
Read guideAT HOME
When you are at home
Where to stay indoors during lightning, what to avoid and why a porch is not proper shelter.
Read guideON THE ROAD
Lightning and your car
How an enclosed metal-topped vehicle provides shelter, and why tyres are not the reason.
Read guide