A total fire ban has been declared today across three state as a trough and front traverse southeastern Australia. Ahead of these, strong northerly winds are dragging a dry and warm air mass from the central interior to the southern and eastern coasts. This is leading to the most widespread total fire ban region so far this season including eastern SA, northern VIC, central NSW. When speaking of fire, combustion requires three basic elements: fuel, heat and oxygen. Weather elements affecting fire behavior, include three main parameters: - The winds (most important): which affects the direction and the rate of spread of fires. Strong winds also fans fires with fresh supply of oxygen (keeping them going for longer periods) as well as helping to dry out fuels in dry environments. - Humidity levels: which affect the fuel moisture content. - Temperature: This affects all other elements. Obviously, the hotter it is the easier it is to start a fire and also the harder it will be to extinguish. Fuel load is simple the amount of material available to burn, i.e. vegetation, etc. This determines how intense the fire will be and is related to how difficult it will be to suppress the fire once it has started. One important factor of the fuel is how much moisture it has. This is known as curing. With higher content of moisture in the vegetation, the harder it will be to burn. Curing is expressed in percentages, i.e. the percentage of dead material within the vegetation. Think of a green bush during the wet season versus a dry bush at the end of the dry season. This is gives an indication of how dry the vegetation is i.e. 50%, 75% or even 95%. The drier the fuel, the fastest the fire is likely to spread. Fire agencies' fire danger ratings are based on a combination of weather and fuel conditions and give an indication on how hard it will be to extinguish the fire not how easy it will be to start it. So this gives an indication of the consequences of a fire if one was to start. During the fire season, fires can start suddenly and without warning. If you live in the bush or outskirts of a city, it is important to keep an eye on the fire danger ratings and the weather conditions as well as have your bushfire plan and kit ready.