In the May & June 2020 issue [1] we presented our new open-source weather station designed here in the Elektor lab. The system consists of a mechanical kit (wind sensors, rain sensors, and housing) as well as the necessary electronics built around an ESP32, all available from the Elektor Store. It reads measurement output values from the sensors and sends them to cloud services such as openSenseMap and ThingSpeak. Hardware is, of course, only part of the project and in this article you will learn how the function blocks of the modular software interact. Thanks to an intelligent Mapper, sensor data can be flexibly linked to communication channels. The web server, which plays a central role in the project, will also be examined in detail in this article.