Weather and Fires

Weather and Fires

Weather plays a part in all the stages of a fire’s life. Wind aids in the progress and drought conditions make for favorable fire conditions.

The three parts of weather that can affect fires are:

·         Temperature

·         Wind

·         Moisture

Temperature is one of the key components of the fire triangle because it generates heat. Warmer temperatures allow fuels to ignite and burn faster. Fires tend to rage in the afternoon hours when the temperature is hottest.

Wind has the biggest and most unpredictable impact on fires. It dries fuels more, provides the fire with another pillar from the fire triangle – oxygen, and pushes the fire further.

Large, violent wildfires can create vertical tilted, masses of swirling air generated by the fire’s heat, these phenomena are called fire whirls. They have been known to hurl debris over large distances.

A fire can generate its own winds that can be up to 10 times faster than surrounding winds. Because of the way winds affect them, fires can sometimes seem like they have a mind of their own – throwing embers into the air and creating more fire, in a process called spotting. Wind can also push fires further up, igniting the canopy of trees, creating a crown fire.

We have discussed factors that help fire, there is another aspect of weather than can hinder fires – moisture. Humidity can go both ways to be a help or be a hindrance to fire. If humidity is low there is less moisture in the air, so fires can ignite. However, if the humidity is high, fuels are less likely to ignite. Rain and other precipitation increase the moisture in fuels and as a result suppress potential wildfires.

If you would like to learn more about how wildfires are affected by fuels, topography and weather you can click here to read more.