We describe the design of a system for wildfire monitoring incorporating wireless sensors, and report results from field testing during prescribed test burns near San Francisco, California. The system is composed of environmental sensors collecting temperature, relative humidity and barometric pressure with an on-board GPS unit attached to a wireless, networked mote. The motes communicate with a base station, which communicates the collected data to software running on a database server. The data can be accessed using a browser-based web application or any other application capable of communicating with the database server. Performance of the monitoring system during two prescribed burns at Pinole Point Regional Park (Contra Costa County, California, near San Francisco) is promising. Sensors within the burn zone recorded the passage of the flame front before being scorched, with temperature increasing, and barometric pressure and humidity decreasing as the flame front advanced. Temperature gradients up to 5 C per second were recorded. The data also show that the temperature slightly decreases and the relative humidity slightly increases from ambient values immediately preceding the flame front, indicating that locally significant weather conditions develop even during relatively cool, slow moving grass fires. The maximum temperature recorded was 95 degrees C, the minimum relative humidity 9%, and barometric pressure dropped by as much as 25 mbar.
