Our society is increasingly reliant on embedded systems for many critical day-to-day activities. Nowadays, Wireless Sensor Networks (WSN) are widely used almost everywhere, including both residential areas, and undeveloped areas near the river. Therefore, embedded systems can reduce risks due to an increase of climate change in Rwanda with potentially devastating impacts of floods on local communities and their properties. Advances in embedded system, particularly in WSN, offer us critical opportunities to develop complex real-time early warning and monitoring systems. The WSN technology has been applied in monitoring natural disasters for the last couple of decades. This paper further proposes an innovative and inexpensive framework designed to provide early warning for natural disaster via a siren. It works by continuously recording and transmitting sensor data to the main server. The server processes the data and then provides the warning, so that vulnerable residents can be notified before the floods come around their houses, especially in high risk zones. The major components of our framework include Arduino, solar panel, flood detector (sensor) with other wireless sensor components, a chargeable battery, Xbee and access point.