Guide to Southwest U.S. Station Climate Summaries

The southwest U.S. has a unique climate characterized by distinct wet and dry seasons that emerge throughout the annual cycle (Sheppard et al. 2002). In Arizona and New Mexico, the annual pattern of precipitation is characterized by rapid onset of the summer monsoon thunderstorm activity in late June that persists through late September and a more gradual onset of winter storms in late October that can persist through the spring. These two rainfall periods set the conditions for seasonal fire activity, streamflow and water supply, and rangeland conditions (Crimmins et al. 2017).