Extreme weather includes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather. The most commonly used definition of extreme weather is based on an event's climatological distribution. Extreme weather occurs only 5% or less of the time. According to climate scientists and meteorological researchers, extreme weather events are rare.

The international reinsurance company Munich Re says that increasingly large numbers of weather-related natural catastrophes are due to climate change, with global warming playing a significant role in the rising number of extreme events such as windstorms and floods which have tripled since 1980, a trend that is expected to persist. According to the National Oceanic and Atmospheric Administration, there were a record twelve weather disasters in the US costing more than $1 billion in 2011. The previous record was nine in 2008.

A 2012 study indicated an increasing threat from extreme weather.

According to IPCC (2011) estimates of annual losses have ranged since 1980 from a few billion to above 200 billion USD (in 2010 dollars), with the highest value for 2005 (the year of Hurricane Katrina). The global weather- and climate-related disaster losses reported over the last few decades reflect mainly monetized direct damages to assets, and are unequally distributed. Loss estimates are lower bound estimates because many impacts, such as loss of human lives, cultural heritage, and ecosystem services, are difficult to value and monetize, and thus they are poorly reflected in estimates of losses.