The term “gerira gouu”(ゲリラ豪雨) refers to the phenomenon of highly localized heavy rain. Though it is not an official term, the expression, which means “guerilla downpour” is used due to the sudden and unpredictable nature of the phenomenon. The typical season for this kind of rainfall is summer, from July to the end of September, though it can occur outside of these months.

Where to find general updates

Japanese TV and radio stations broadcast advance warnings with the expected time and area of landfall. The most authoritative source of information about guerrilla rain in Japan is the Japan Meteorological Agency.

Look out for emergency announcements—you’ll find out whether any special precautions or actions need to be taken. If you don’t speak Japanese, you can tune into NHK World News, which provides official information in English.

How can I prepare for guerrilla rain in advance?

Watch for sudden weather changes.

・Have an emergency kit ready at home and, ideally, at work too (you can make one yourself or buy one online, e.g. on Amazon)

・Familiarize yourself with the location of evacuation shelters in your area.

・Make a plan of action with your partner, family or housemates.

We also recommend checking the Disaster Prevention Portal, which provides useful disaster prevention information in English and other languages.

Things to have on hand

●Flashlight (with fresh batteries)

●Non-perishable food

●Phone charger

●Spare change of clothes

●Rain gear

●Cash, credit/bank cards

●ID card and/or passport