All weather data (including SizingPeriod:DesignDay and Site:Location validation) are processed by the WeatherManager module. The SimulationManager invokes the WeatherManager at the proper times to retrieve data. The WeatherManager will retrieve the proper data for the current timestep/hour/day/month from the proper data source (design day definition, weather data file). The WeatherManager puts weather-type data (outside dry bulb, outside wet bulb, humidity, barometric pressure) into the DataEnvironment global data area. There is no need for other modules to call the WeatherManager directly. However, if there is some weather-type data that is needed and not provided in the DataEnvironment global area, contact us.