To minimize the aforementioned damages, early detection of environmental hazards like forest fires is critical. It is also very important to have early and accurate information about the exact origin(s) of the fire and its course as it spreads. Great technology effort has been invested on the design of systems for fire detection and monitoring. From an engineering perspective, machineries can be designed and used to help with detection or prediction of the disastrous events. One technology that enables (near) real-time detection of such events is the so-called Wireless Sensor Networks (WSNs). WSNs typically consist of a large number of small, low-cost sensor nodes distributed over a large area. The sensor nodes are integrated with sensing, processing and wireless communication capabilities. A simple WSN could be based only on a network of multi-sensor field devices that are able to detect increases in the temperature and/or decreases in the humidity percentage. However, the most promising approach for the early forest fire detection in WUI zones is the combination of various heterogeneous sensors. Typical temperature and humidity sensors can be combined with video-capable wireless sensors, optimally placed in an area of interest, to better observe the outbreaks of various hazardous phenomena. The prediction accuracy of such an approach could be enhanced through the exploitation of remote sensing products such as satellite monitoring (another source of information interfaced to the systems). Of course, one of the requirements that have to be addressed is the optimal placement of the available sensor infrastructure in order to maximize the coverage of the monitored area. WSN systems can reach, at a reasonable cost, the density of physical parameter measurements needed for an accurate and timely fire detection, localization and progress monitoring.