What is the difference between weather and climate? Climate is generally defined as ‘the average weather’. ‘Weather versus climate’ looks at how scientists make predictions about weather and climate change. Accurately predicting weather is difficult. Chaos theory tells us that we can predict within certain boundaries what the weather will be like; when it comes to detailed predictions, everything breaks down due to the ‘butterfly effect’: small changes may multiply and cascade upwards to cause big swings in weather. Climate models of recent years have provided consistent answers meaning that we can start to understand the consequences of past and future actions.