AUSTIN (KXAN) — The length of a given wildfire season is increasing for much of the country. The largest increase is occurring in the west, especially in the southwest during its increasingly hotter summers. Weather conditions with low humidity, extreme heat, and strong winds are all conducive for the spread of fire. A single day with all of these ingredients combined is considered a ‘Fire Weather Day.’
Our partners over at Climate Central looked at climate data at weather sites across much of the nation over the course of 50 years. What they found is that overall, ‘Fire Weather Days’ are increasing across the majority of the nation with an increase of +2 days for us here in Austin.
However, that number drastically jumps upwards the further south or west you head in the state. South Texas is seeing a jump in up to a 13-day increase over the course of 50 years while portions of West Texas has seen an alarming jump of 58 more ‘Fire Weather Days.’
In fact, portions of the state are experiencing nearly two more months of fire weather compared to a half century ago. According to Climate Central, “parts of Texas, California, Oregon, and Washington, are experiencing fire weather more than twice as often now than in the early 1970s.”
While the length of wildfire seasons continue to grow, they are also becoming more intense and oftentimes more difficult to contain.
Much of the East however is seeing more minimal changing impacts. But even with just a small increase, this still puts millions of more people and homes at risk. Analysis also found that coastal areas especially haven’t seen substantial changes over the past several decades because high humidity always has and continues to be a part of their climate. A result of the close proximity to the ocean. (High humidity decreases the risk of fire)
According to Climate Central “parts of Idaho, North Dakota, and South Dakota have experienced a decline in the frequency of fire weather days. The Dakotas are part of a region where springs have been cooling slightly — likely a temporary trend influenced by the cooling effects of agricultural development.”
How is climate change playing a role?
As temperatures continue to increase across the globe, this will continue to be one of the main ingredients that will influence the behavior of fires and and provide additional fuel which will make conditions initially more conducive to ignite. Climate Central says we can expect warmer nighttime temperatures and lower humidity. This is problematic because in decades in the past, nighttime would be the narrow window of the day where firefighters would be able to gain control over a wildfire. Overnight hours used to be more associated with higher humidity which would help firefighters gain control over wildfires (this is now not so much the case anymore).
As humidity continues to decrease, more moisture is being pulled out from plants and other vegetation and brought into the air. This process is called evapotranspiration. This however is bad because it further increases the risk of fire as the vegetation becomes dry and more prone to be burned.
How this impacts us
As wildfire seasons become more intense and continue to lengthen, the window of opportunity for fire fighters to conduct prescribed burns decreases. Weather conditions for prescribed burning need to fall under a specific criteria, generally including high humidity, relatively cooler temperatures and calm to light winds.
Now with fewer days left to conduct these prescribed burns, more fuel for future wildfires will build up as dried vegetation stacks up overtime across a landscape. This could further exacerbate the intensity and scale of a future wildfire.
Wildfire smoke can also travel thousands of miles and affect areas well downstream and away from the fire. We’ve seen often our air quality deteriorates when a wildfire becomes intense out thousands of miles away out west and the right wind weather pattern sets up to bring that smoke all the way to our area.
