Rain? What is that?
Regarding Malibu:
Malibu, with its dry chaparral brush and north-to-south running canyons, makes ideal turf for Santa Ana wind-driven flames. The Malibu area hosts one of the most combustible types of brush in existence, the chaparral ecosystem. Chaparral consists of many small, woody plants that are full of oils and are extremely flammable. These plants also tend to occur in very dry climates, and are drought-resistant. But the vegetation's most dangerous trait is its tendency to burn every 15 to 45 years in its own natural reproductive cycle, to eliminate old growth and begin the regenerative process. Inhabitants make the problem worse. Small fires are extinguished in the Malibu hills as soon as they threaten homes. But preventing the remaining plants from burning causes large amounts of old, dry brush to build up in Malibu's canyons, providing massive quantities of flammable material.
The Las Virgenes/Malibu Canyon corridor provides a fertile playground for wildfires, with its steep walls and high-velocity winds. The growing population north of the canyon creates many opportunities for accidental triggers or arson to start a major fire.
During the fall and early winter months, strong Santa Ana winds take regular trips through Malibu and out to the ocean. As the Santa Ana winds blow through, evaporating whatever moisture is left in the chaparral after the long dry summer, relative humidity can drop below 10 percent. Once a fire starts, it is nearly impossible to contain, until the Santa Ana winds die down. Malibu has a history of wildfires which "historically follow well-defined wildfire corridors. When large and damaging fires occur you'll find the wind and fire corridors perfectly aligned." (report 4) This makes it even more difficult to fight a fire.
http://www.malibucomplete.com/mc_hazards_fires.php