That is the thing you don't think about initially, the heat causes the air to rise and pull in more oxygen to fuel the fire even more.
My brother is looking at building a house in a "fire area" as in an area that has never burnt either, but the council says you need to ensure all the outside is fire proof and wire mesh for where embers can touch timber (like crimsafe). I'd like to think it would never burn from an ember, but when embers are flying at your house like the sparks from a grinder, it is more likely one will start a fire.