Santa Ana Winds=Wildfires=southern California in the fall and early winter. High pressure over the Rocky Mountain States creates an easterly wind over southern California. (Remember winds blow clockwise around high pressure). The easterly winds go up the Santa Ana mountain range and then the air descends and blows hard into southern California. When air goes up, the parcels of air expand and cool. When the air parcels descend they compress, heat up and dry. It is the hot and dry wind that creates perfect conditions for wildfires and is the recipe for disaster.

Now you have to keep in mind this is all part of a natural process in that part of the country. Wet periods grow new brush. Dry periods dry the landscape and then the Santa Ana's burning the land. Problem is man has moved into these areas that go through the process putting lives at risk.

In a way it is comparable to the population boom along the Atlantic and Gulf coasts. A tremendous increase in the number of people that now live along the coasts are at a much higher risk from hurricanes.