The main purpose of thermal insulation is to reduce the effect of weather conditions, which can reduce energy consumption and help preserve the natural environment. Due to increasing demand for thermal insulation in modern buildings, it is necessary to monitor the effects of weather condition on the efficiency of thermal insulation. To measure this effect, Internet of Things (IoT)-based sensor networks play an important role. This paper proposes an IoT-based monitoring system that measures and analyses the effect of weather conditions on thermal insulation efficiency. The proposed system includes an Arduino as a central unit that interfaces at the input with temperature and relatively humidity sensors, and at the output with a WiFi module that transmit the collected data via the Internet to an IoT analytics platform to aggregate, analyze, and visualize the data. The proposed system is low cost and provides insight into the design and implementation of a complete application with important IoT features, e.g., sensing and transmitting data to the cloud, data processing, and data retrieval through the ThingSpeak open-source API. In a proof of concept, the proposed system was implemented and tested in different environments and at different altitudes, and the results were analyzed and compared to standard weather data. The sensed data can be further analyzed and leveraged by end users to mitigate the effects of weather conditions on thermal insulation.