The Weather Guide for the Canadian Forest Fire Danger Rating System is intended primarily for operational wildland fire management personnel and forest fire weather practitioners responsible for gathering, processing, and forecasting fire weather information in support of safe and effective suppression and use of fire. Accurate and representative weather observations that meet prescribed standards and specifications are necessary for accurate and representative calculation of all components of the Canadian Forest Fire Danger Rating System. Weather-dependent components or modules are calculated or computed for effective use of the system's two main subsystems, the Canadian Forest Fire Weather Index (FWI) System and the Canadian Forest Fire Behavior Prediction (FBP) System. This weather guide includes detailed specifications for locating and instrumenting fire weather stations, taking weather observations, and overwintering the Drought Code component of the FWI System. The sensitivity of the FWI System components to weather elements is represented quantitatively. The importance of weather that is not directly observable is discussed in the context of fuel moisture and fire behavior. Current developments in the observation and measurement of fire weather and the forecasting of fire danger are discussed, along with the implications for the reporting of fire weather of increasingly automated fire management information systems.