Abstract: A monitoring system includes monitoring devices monitoring respective refrigerated storage units to measure internal temperature values and door status values representing the door being opened or closed. The devices periodically report the data to a computer server that stores the data in a database in respective database records associated with the monitoring devices respectively so that each database record includes a time series of the internal temperature values and a time series of door status values representing the door status over time. The server is able to generate reports which graphically represent both the internal temperature values and the door status values over a selected time range. User configurable alert criteria associated with the monitoring devices includes a temperature criterium, a door criterium, and a duration criterium for generating notifications when user attention is required.