There may be two aspects in forest fires i.e. i) detection & mapping and ii) monitoring. For detection and mapping, best option is to go for remote sensing (airborne/spaceborne) data/imageries e.g. Thermal IR data/imageries and measure the high temperature zones. Other data (Visible/IR) are also used for additional information extraction.
For monitoring the forest fires, one has to go for multi-temporal TIR data and check how the forest fire is advancing and at what rate, whether they can be controlled, and which area needs maximum surveillance etc. Day-to-day (or even less hours) monitoring may as well be needed in case of severe forest fires.
Here you can find a methodology to map the rural-urban interface, an area where human-induced fires are more likely to occour, avoiding a rigid definition of its boundaries:
Article Fuzzy definition of Rural Urban Interface: An application ba...