Most of us are familiar with tornadoes; rotating columns of air that usually form above the warm oceans in tropical areas. The strength of tornadoes is measured from F0 to F5 on the Fujita scale. Alternatively, fire tornadoes—also known as fire whirls or fire devils—are much less known. This is basically because they are very rare and usually happen in settings one would typically escape such as wildfires. Perhaps you saw fire tornadoes for the first time in the videos of the California 2025 wildfires.
Fire tornadoes are in fact whirls, and that is good news since the strongest whirl is much weaker the weakest tornado. A fire whirl is a spinning air column that carries heat, ash, and flames. It is very difficult to study fire whirls, since it is impossible for scientists to step into the fire even through their tools and gadgets.
Fire whirls form within wild fires as the resulting heat starts to establish its own wind system. As the heat rises rapidly and continuously, it leaves behind a void area. Then, the air in contact with the fire comes in to fill this void area, originating a rising air current that may lead to the formation of a fire whirl.
When the fire smoke rises, water vapor condenses as it reaches the upper layers of the atmosphere, forming clouds known as flammagenitus clouds. If it was a massive fire, flammagenitus clouds could cause lightning that can start new fires. It may also generate strong winds that contribute to spreading it.
Fire whirls range from 91 to 122 meters in height, and 6 to 15 meters in width. The temperature inside the air column reaches 1093 degrees Celsius, while the wind speed ranges from 161 to 483 km. Fire whirls can last from several minutes up to an hour.
Fire whirls occur in extremely tough conditions and intensify wildfires. One of the most notorious incidents is the Great Peshtigo Fire, which took place in the United States in 1871. In this incident, strong winds that blew in a dry summer day transformed small prairie fires into a massive one. Peshtigo had many wooden structures, cut timber, and pine shacks, which provided fuel to feed the growing fire. Fire whirls were also spotted in Palisades Fire on 10 January 2025, where wind speed reached 112 km/hour.
References
apnews.com
science.howstuffworks.com
scijinks.gov