Climate change impacts water, sanitation and hygiene (WASH) and agriculture programs, and threatens development progress. Climate information services (CIS), sometimes known as hydrometeorological systems, are a series of powerful tools and resources that can improve planning, reduce risk, and increase resilience. This brief from PRO-WASH and SCALE introduces CIS, and describes how CIS can be used by resilience food security activities 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.