In this paper we identify twelve areas of research and activities that can improve our understanding of weather and climate extremes. Many of these research areas and activities are consistent with previous reports, especially the CCSP SAP 1.1 report on reconciling temperature trends between the surface and free atmosphere.

Many types of extremes, such as excessively hot and cold days, drought, and heavy precipitation show changes over North America consistent with observed warming of the climate. Regarding future changes, model projections show large changes in warm and cold days consistent with projected warming of the climate by the end of the 21st century. However, there remains uncertainty in both observed changes, due to the quality and homogeneity of the observations, and in model projection, due to constraints in model formulation, in a number of other types of climate extremes, including tropical cyclones, extratropical cyclones, tornadoes, and thunderstorms.