Climate change means a change in average weather conditions (such as rainfall, temperature or humidity) over years or decades. Climate change impacts water, sanitation and hygiene (WASH) and agriculture programs, and threatens progress. Climate information services (CIS), sometimes known as hydrometeorological systems, are a series of powerful tools and resources that can help to improve planning, reduce risk and increase resilience. CIS include weather radars, satellites, water level meters and other hardware that monitors physical parameters, such as air and sea temperature, humidity, river flows, wind velocity and barometric pressure. Just as important are the social and institutional systems and the people who support and link this hardware. CIS also include applied climate research and climate modeling that interprets the data and results and, in turn, feeds back into the CIS design so that the CIS becomes more accurate over time. CIS also include reports, risk assessments, forecasts, warnings, expert opinions and tools. This brief introduces CIS and describes how CIS can be used by resilience food security activities (RFSAs) and partners. The brief lists resources for CIS and shows where more information can be found. It also introduces national, regional and global CIS providers and partners.