CoCoRaHS is a network of volunteer weather observers that was developed in 1998 to collect precipitation data and provide more detailed observations than traditional weather stations. Volunteers measure daily rain, hail and snow in their local areas to help the National Weather Service and other organizations improve weather forecasting, public safety, and environmental understanding. The program now has over 18,000 observers across all 50 states providing real-time data that is mapped and used for research, education, and other benefits.