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Data Update Cycle
The cycle time for update is 5 minutes.
To view the latest data, click the key "Refresh"on the tool bar.
The update may halt temporalily due to radar maintenance or other inspection.
Discriptions in the table below refer to the situation on the ground as generalized image for each rainfall intensity.
It should be noted that radar meaures the intensity high above the ground, which is not necessarily consistent with the intensity low on the ground.
Expression in legends Human impression Effect for humans Situation of indoors
(wooden house)
Situation of outdoors Effect for a driver Possibility of disaster
Drizzle       Ground gets wet    
Moderate       Puddles sparsely    
Slightly Strong Sound audible Splash wets footwear Conversation disturbed Puddles all around   Need to be cautious when it continues
Strong Feel force or strength of rain Umbrella works insufficiently Clamorous sound of raindrops disturbs sleep, e.g. awakes more than half of sleepers. Poor vision with fast wiper Overflow from roadside gutters, wastewater drains or small streams
Occurrence of small-scale mudslide
Rather Fierce Feel like buckets of water poured over Puddles make a road like a river Risk for hydroplaning (Occurrence of water film between wheel and ground) Mudslides or even landslides are prone.
Preparation for evacuation is necessary in dangerous zone.
Overflow from discharge pipelines in cities.
Bitter Fierce
Severe Torrential Umbrella is useless White landscape and poor vision Driving is dangerous Rainwater runs into underground cells or shopping mall
Sprouts from manholes
Brings other disasters
Extreme Severe Feel fright with choking pressure Large-scale disaster is possible.
Highest alert is needed.

Data quoted from Japan Meteorological Agency (Data as of August, 2000, revised in July,2002).

[ Notes ]
The table assumes the continuation of one-hour for each rainfall intensity.

  1. The degree of disater varies with conditions of initial intensity or topological feature.
  2. The descriptions are based on recent cases.. Alteration should be done for deviation from actual situation.

JR Lines displays JR Lines in the map. companiesLine displays other companies’ line, subway is not included.
stationMark means the place of each station.
Weather Warnings and Advisories
Japan Meteorological Agency issues heavy rain emergency warnings/warnings/advisories to call attention or precaution expecting damage possible.
All types of information written below will be shown in this site when announced by JMA.
Heavy rain、Storm、Snow-storm、Heavy snow、High waves、Storm surge
Warning Heavy rain、Flood、Storm、Snow-storm、Heavy snow、High waves、Storm surge
Advisory Heavy rain、Flood、Gale、Gale and snow、Heavy snow、High waves、Storm surge、Thunderstorm、Snow melting、Dense fog、 Dry air、Avalanche、Low temperature、Frost、Ice accretion、Snow accretion

About emergency warnings/warnings/advisories, refer to JMA-HP.

The standard of warnings/advisories for Tokyo Metropolitan Area , only japanese

Examples of municipal and resident responses to weather Warnings/Advisories

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Contact Us
  • Please send your commments to:.
    Consultation and Service Desk
    Public Relations and Service Section, General Affairs Division
    Bureau of Sewerage, Tokyo Metropolitan of Government
  • 163-8001 Nishi Shinjuku 2-8-1,Shinjuku-ku,Tokyo
  • Telephone:03-5320-6511(Direct)
  • Fax:03-5388-1700(Direct)
  • E-Mail form: Click here to send your e-mail.
  • Reception time:8:30~17:15(Weekdays)
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