Colorado wildfires flare up every summer, often threatening the state’s population centers and wild areas, alike. As a result, scientists and firefighters follow climatic and environmental patterns closely each year in an attempt to better predict fire danger and to prepare for necessary mitigation.
“The risk of large wildfires and severe wildfire seasons are definitely correlated with drought years and low snowpack,” says Becky Bolinger, Assistant State Climatologist at CSU’s Colorado Climate Center. “Our worst fire seasons are connected to bad drought years and low snowpack.”
In 2002, 2012, and 2018, very low winter snowpacks were certainly followed by especially severe fire seasons. The year of 2002 brought unprecedented drought to Colorado. That February, parts of Southern Colorado had only reached 40-50% of the average snowpack. Months later, the 2002 Hayman Fire was the largest in state history, burning a total of 138,000 acres just northwest of Woodland Park.
This year’s snowpack is on track to be slightly above the five-year median, according to the National Resources Conservation Service. Some hope that fire risk will be lower thanks to this healthy level of snowpack.
However, the relationship between snowpack and fire season severity isn’t exactly clear cut. Low snowpack is a bad sign, but exceptionally high snowpack and precipitation years can worsen wildfire risk, too.
“Wet winters and springs can also favor increased wildfire risk due to increased understory growth,” says Colorado College ecology professor Dr. Brian Linkhart. “The difference here is that these fires typically occur later, in the summer or in the fall, after the increased understory (grasses and low-lying plants) have had a chance to dry out.”
The drier the plant growth, the more likely this source of “fuel” is to burn. NOAA keeps track of fuel moisture–the amount of water in plant growth–across the country as an indicator of potential fire danger.
Most years, the eastern plains tend to see the first fire risk of the season as early as March.
“[The eastern plains] are currently in a time period where windy days become common,” explains Bolinger. “Add in low relative humidities and warm days and they are likely to experience some red flag warnings in the coming weeks.”
This is considered normal. May generally brings a lull in the fire season statewide due to precipitation and spring green-up. Fire season in the mountains tends to start in June and run through the rest of the summer.
“The severity of the fire season in Colorado is moreso driven by what happens from February through April. This timeframe can really define what the fire season will look like, ” says Rocco Snart, fire behavior analyst with the Colorado Division of Fire Prevention and Control. “It is still too early to tell what 2020 will bring.”
Colorados’ persistent drought is likely to continue to be a factor in severe fire seasons. In recent years, much of Colorado has been consistently considered “abnormally dry” or worse, a trend expected, by some, to continue.