What is ‘extreme’ weather? Why are people talking about it these days? ‘Extreme’ weather is an unusual weather event such as rainfall, a drought or a heat wave in the wrong place or at the wrong time. In theory, they are very rare. But these days, our TV screens are constantly showing such extreme weather events. Take just three news stories from 2010: 28 centimetres of rain fell on Rio de Janeiro in 24 hours, Nashville, USA, had 33 centimetres of rain in two days and there was record rainfall in Pakistan.