Why Are Winter Wildfires Increasing in Frequency?

Forest fires in winter

"Winter wildfire is an oxymoron,” says Jennifer Balch.

The associate professor of geography at the University of Colorado Boulder specializes in fire ecology, and she’s one of many noticing a common trend.

Warmer temperatures in July, August, and September used to pair with dry winds to constitute the fire season. But with the changing temperature trends across the globe, wildfires are no longer restricted to a specific season. Dry vegetation and strong air currents provide the perfect ingredients to give rise to raging infernos.

The 2021 to 2022 winter witnessed two significant fires in Colorado and California, along with dozens of smaller fires all over. Winter wildfires were once a rare anomaly, but they have unfortunately become more common today. And experts like Balch claim that the frequency of winter blazes is bound to increase in the coming years.

Let’s examine the causes of winter wildfires and the factors that make them so common.

3 Causes Of Winter Wildfires

Wildfires in winter should be rare because the cold, damp environment not only makes it hard to start a fire, but it also extinguishes any flames. Yet, we now experience several unexpected fire events in December and January due to extreme temperature changes.

Here is a list of factors fanning potent flames:

1. Contraction Of Rain Spells

Typically, most areas get a good rainstorm by December, settling the wet season. Hence, the natural fuels of the fire are no longer flammable and pose little to no risk of creating a spark.

But recent years have been different.

Due to the shortage of rain and frequent droughts, climates that are normally wet have become drier and more prone to combustion. For example, less precipitation means dry vegetation–the perfect fuel for a winter forest fire.

2. Strong, Dry Winds

Intense and dry winds characterize fall throughout America. When combined with warm weather, these winds are a potential fire hazard. Usually, that isn’t a problem because a wet, cold winter follows.

But as the temperature rises globally and there are more severe droughts, winters have become warmer and drier. The winter winds start as masses of cool air in the mountains before migrating towards the coastal area due to high-pressure ridges.

These winter winds will soon gain warmth and speed, easily turning a tiny spark into a relentless inferno when combined with dry weather conditions.

3. Dry Snow

You would think that fire in snow is an uncommon sight, but recent climatic anomalies prove the notion wrong. When an area does not receive enough rain in the fall, the first snow of the season is dry.

As a result, the trees and leaves buried under this layer of dry snow are still dry enough to keep burning. Another issue is that dry snow has enough oxygen to keep a fire alive but lacks the water content to extinguish it.

What Makes Winter Wildfires So Common?

In recent years, firefighters have had to deal with massive blazes over the holidays far too often. Not to mention, more and more families are forced to evacuate at a time when they should be home with loved ones.

Here are the 4 chief factors that contribute to the frequency of the scenario:

1 - Frequent & Longer Droughts

As the climates become more extreme, more regions are falling prey to longer droughts in winter. This means trees, shrubs, and grass all dry out, providing essential fuel for ignition. The result? Dry vegetation causes winter wildfires to spread rapidly because they’re highly combustible.

2 - Human Encroachment in Fire-Zones

Environmentalists refer to the current era as the Anthropocene Epoch, as it's a period of time heavily influenced by human activities. In the Anthropocene Epoch, winter wildfires are a direct result of humanity’s impact on our environment.

The further humanity encroaches into nature and fire-prone zones, the more winter wildfires we’ll see.

3 - Non-Strategic Reforestation

For years, the Canadian federal government has focused on planting trees in post-fire areas. But in April 2016, Canada experienced an enormous wildfire that became the costliest natural disaster in the country’s history. While studying the causes of the fire, experts found that ambitious reforestation can be a double-edged sword.

When tree planting initiatives fail to use correct reforestation strategies, they drain extensive swamps of their natural groundwater. Because of this, trees will grow into overcrowded woodlands. Places where forests are not supposed to exist.

The result is a dangerously low water table, weaker plants, and even more fuel to burn.

4 - Invasive Species And Tree Mortality

Over the next 30 years, scientists claim that invasive insects will kill approximately 1.4 million street trees. Species like the bark beetle quickly spread across borders through human activities such as trade and travel – and the harm these species are doing is serious.

Such species, like the bark beetle, damage certain trees, turning them into easily combustible masses of timber. When the conditions are suitable, they can catch a small spark and set acres of land ablaze.

How To Measure Air Pollution During A Wildfire?

Air pollution is one of the gravest consequences of wildfires. When thousands of trees burn, they emit their carbon content into the atmosphere – polluting the air we all rely on. The best way to stay informed is by using commercial air quality monitors.

Monitor the Particulate Matter levels around the world with our free, real-time PurpleAir Map or join PurpleAir's mission to make air quality data accessible to everyone by investing in an air quality monitor for your home. 

Together, we can be informed and make changes in our daily habits and the community to improve air quality.