Austin has had 5 high risk wildfire days this month alone. Why are there so many red flag warnings?

As Texas becomes hotter and drier, and urban sprawl grows, the state could see more days with an elevated risk for wildfires.

So far this year, Austin has had five of these days, also known as red flag warning days, and all of them have been in March.

Texas State Climatologist John Nielsen-Gammon said over the last 20 to 25 years Texas has seen many large wildfires. He said a combination of human activity and climate change are contributing factors to those fires. The risk levels, though, are going to vary from year-to-year and can also depend on weather patterns, he said.

“La Niña, which is when the tropical Pacific is unusually cold, tends to lead to drier winters in Texas and stronger winds in springtime,” Nielsen-Gammon said. “So it’s not surprising that we are seeing wildfire risk during this particular year.”

There are three main factors meteorologists consider when determining if the wildfire risk is enough to issue red flag warning. Bob Fogarty, a meteorologist with the National Weather Service, said those alerts happen when grasses, brush and trees are really dry; the relative humidity, or the amount of moisture in the air, is less than or equal to 20% and winds reach 15 mph or greater.

“The thing that we are really looking at is the weather doesn’t usually cause the fire, it causes the fire to move rapidly,” he said. “When we get really dry conditions and really strong winds, any fires that start can get out of control quickly.”

This was the case when a fire broke out near Fredericksburg on Saturday. Initial estimates of its size started at 400 acres, but the strong winds and dry air helped fuel the fire that grew to more than 9,800 acres. As of Wednesday, the fire is about 90% contained, according to the Texas A&M Forest Service.

Fogarty said springtime is traditionally when these warnings happen, because it’s before the vegetation starts to green and before any significant rain falls.

“We’ve been in a drought and haven’t had much rain, so the fuels, like grasses, are really dry,” he said.

Nielsen-Gammon said red flag warnings could become more common as higher temperatures and very dry conditions develop earlier in the year, extending both the spring and summer wildfire seasons.

“Climate change enhances the rate at which fuels dry out faster, because higher temperatures allow for a greater rate at which water evaporates, making them prime for burning,” Nielsen-Gammon said. “There is not a clear climate change connection with the high winds, but having fuels ready to burn can happen more frequently because of climate change.”

There are also parts of the state that have seen increased risks wildfires because of changes in landscape, he said. Nielsen-Gammon said many rural areas went from open pastures to more brushy landscapes, as people move farther out from big cities.

“When you have a wildland urban interface where people live in more rural areas, these areas then include more trees and houses being built, which is fuel for wildfires,” he said.

But many wildfires are caused by humans, Nielsen-Gammon said, and there are ways to prevent them.

When conditions are dry and windy, Fogarty said people should be careful about causing a fire, and avoid dragging tow chains, leaving a hot car on dry grass, or using open flame on fire or barbecue pits.

Travis County issued a burn ban at the beginning of March that will remain in effect until at least April 8. Travis County Judge Andy Brown also signed a disaster declaration that allows the county to prepare for neighborhood evacuations and tap into state resources.