Extreme weather is defined as severe, usually unexpected hazards that are out of the ordinary. Floods, droughts heat waves and bush fires are examples of extreme weather. Too much or too little precipitation, change in temperature, or high pressure systems create hazards which affect people all over the world. Scientists say winter weather in the United Kingdom is growing more extreme which could be due to 'random fluctuations in the climate system'. The changes in air pressure over the North Atlantic Ocean has resulted in five out of the ten most extreme winters of the last century to occur in the past decade. This shows that the climate has become increasingly unsettled which has resulted in numerous accounts of extreme weather. These extreme winter weather events are mirrored throughout the summer months where there have been heat waves and droughts which are followed by flooding.

Scientists believe that it is impossible to relate any one specific extreme weather occurrence to climate change, despite the fact that extreme weather is growing more often. Despite the confusion surrounding what is generating extreme weather, it is obvious that the planet is warming up and severe weather is occurring everywhere. The International Disaster Database's records show that during the 1960s, there have been significantly more flood and windstorm disasters, and these occurrences have been more severe, prolonged, and widespread. Most climate models indicate an increase in the frequency and length of extreme events. Scientists use climate models to predict patterns of future heat waves. From the evidence of past events, the Intergovernmental Panel on Climate Change (IPCC) is confident that certain weather events will become more frequent, widespread and intense as climate changes.