Extreme weather includes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather.

Increasing dramatic weather catastrophes are due to an increase in the number of severe events and an increase in population densities, which increase the number of people affected and damage caused by an event of given severity. The World Meteorological Organization and the U.S. Environmental Protection Agency have linked increasing extreme weather events to global warming, as have Hoyos et al. (2006), writing that the increasing number of category 4 and 5 hurricanes is directly linked to increasing temperatures. Similarly, Kerry Emmanuel in Nature writes that hurricane power dissipation is highly correlated with temperature, reflecting global warming. Hurricane modeling has produced similar results, finding that hurricanes, simulated under warmer, high CO2 conditions, are more intense than under present-day conditions. Thomas Knutson and Robert E. Tuleya of the NOAA stated in 2004 that warming induced by greenhouse gas may lead to increasing occurrence of highly destructive category-5 storms. Vecchi and Soden find that wind shear, the increase of which acts to inhibit tropical cyclones, also changes in model-projections of global warming. There are projected increases of wind shear in the tropical Atlantic and East Pacific associated with the deceleration of the Walker circulation, as well as decreases of wind shear in the western and central Pacific. The study does not make claims about the net effect on Atlantic and East Pacific hurricanes of the warming and moistening atmospheres, and the model-projected increases in Atlantic wind shear.

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