Changes to weather and climate extremes are likely to become the most vivid and disruptive manifestations of climate change over the course of this century. While it is already understood that human-induced global warming increases the intensity and occurrence of extreme temperatures and precipitation, evidence suggests that hurricanes will also become more ferocious as the world warms. This report constitutes the first specific assessment of observed and projected changes in weather and climate extremes across North America--it details what is already known about extreme climate and weather, explains the understood causes of those events, offers projections of future weather and climate extremes, and suggests how scientific efforts can be better directed to increase understanding of this subject.