“Wildfires burning thousands of acres”
“Homes have been evacuated after a wildfire spreads into local communities.”
“The weather is helping firefighters battle the wildfire blaze.”
Sound familiar? Each year, wildfires top headlines as they rage across thousands of acres of land and destroy hundreds of homes. According to the National Interagency Fire Center (NIFC), an average of over 58,000 fires burned over 6.3 million acres of land in the United States from 2005-2014. 2015 has proven to be a historic year so far, with a little over 8.7 million acres of land burned through September 14, 2015. This is the highest total since 2005, even though the number of actual wildfires (45,491 as of September 14, 2015) only ranks the 7th highest since 2005. Did you know weather plays a crucial role in creating, maintaining and fighting wildfires? It dictates how wildfires react, when Red Flag Warnings or Fire Weather Watches are issued, and when firefighters are sent to battle the blaze. Let’s explore how weather can start or quell wildfires.
.png)
The three main weather conditions that influence wildfires are temperature, humidity and wind. The ideal set-up for wildfire development is a hot day, with low humidity and a stiff breeze. Why? First, hot and dry air will increase the flammability of potential tinder such as grass and shrubs which act as a very efficient fuel source for fires. It’s no coincidence that some of the most devastating wildfires typically occur west of the Rockies where we often find some of the hottest and driest air in the country. Once hot and dry conditions are in place, all it takes is a spark either from natural (i.e lightning) or human (i.e cigarette buds) sources to start a fire. What causes fires to become so devastating often is attributed to strong winds that can feed oxygen to fires and enable flames to spread rapidly.
.png)
Of course, wildfires do not burn forever and the weather can just as easily aid firefighters’ efforts. Cool and humid air decreases the flammability of tinder and calm wind help deprive wildfires of oxygen. While it may be thought that rain can help control wildfires, the extremely hot and dry conditions surrounding rampant fires actually creates a microclimate that can evaporates natural precipitation before it can reach fires.
The most favorable time of year for a region to experience the combination of hot temperatures, low humidity, and strong winds is in the spring and autumn for much of the United States. However, nearly ideal conditions for wildfires develop across the West during the fall. The summer is the dry season for many west of the Rockies when places like San Diego, CA and Boise, ID typically receive less than an inch of rain from June to October. With hot and dry conditions in place and gusty winds from Canadian cold fronts and local influences like Santa Ana winds, forests are ripe for wildfires by the time autumn rolls around. In fact, 2015 has been a particular dangerous year for wildfires due to the historic California drought.
No matter the time of year, it’s important to keep fire safety in mind and to ensure all burning objects are attended to and watered down completely. Even with ideal weather conditions in place, humans cause 90% of all wildfires, according to the NIFC, so we can help save the environment by taking all proper precautions.
