An environmental think tank from Germany has revealed that Japan was the worst-hit country by extreme weather in 2018.

Japan experienced record torrential downpours and prolonged heat waves last year.

Scientists at Germanwatch released the information to reporters on Wednesday at the UN climate change conference, COP25, currently ongoing in Madrid, Spain.

The think tank's report ranks countries according to their vulnerability to extreme weather events. Japan ranked first in terms of fatalities and economic loss.

The ranking is a result of deadly torrential downpours that pounded western Japan in July, as well as Typhoon Jebi, that made landfall in western Japan in September while maintaining extreme strength.

In addition, much of Japan was hit by persistent extreme heat in July and August, with the mercury soaring to a record 41.1 degrees Celsius in Kumagaya City near Tokyo in July.

The think tank officials note that multiple extreme weather occurrences in a single year would not have happened if it were not for global warming.

They say that in the past 20 years, nearly 500,000 people died worldwide and losses of 3.54 trillion dollars were incurred as a direct result of extreme weather events.