Warming induced by anthropogenic emissions of greenhouse gases can induce changes in precipitation and other components of the water cycle. Understanding the regional and global changes of precipitation and hydrologic extremes is important for improving societal resilience to environmental changes. The seasonal cycle of precipitation is dominantly influenced by the annual cycle of solar insolation and land-sea contrast, but even precipitation seasonality can be altered by global warming in many ways, with implications for floods, droughts, wildfires, and food production. For example, warming may amplify the seasonal cycle of precipitation in the U.S. Pacific Northwest, but sharpen the wet season in California with Mediterranean climate. Warming may also delay the seasonal migration of the tropical rain belt and the onset of monsoon rainfall. Thermodynamic effect from increasing moisture with warmer temperature plays an important role in these seasonality changes, so climate models show rather robust signals that increase with global warming in the future.