Originally published in Lake of the Woods Area News, Volume 55, Number 5, Winter 2025
The 2025 spring fire season took the Kenora area by surprise with its intensity so early.
There were many factors and causes that created perfect conditions for fires this spring. Many ask why or don’t understand what was happening especially the long time that evacuations and fire statuses were not changed. We will discuss the issues and give a bit of the science behind the decisions made.
The spring of 2025 lacked significant rainfall. The snow melted off before the ground thawed and without being turned into rainfall to soak in. We had a heat spell of unseasonal high temperatures in early May. A major sign of spring is the deciduous trees taking on a dark green for forest fire fighters. This didn’t happen until mid-June as the warm rain didn’t come until then. Some were still not seeing that rich green even in July. This marked an early fire season as MNRF watched the forests and prepared. Early May started with Ken14 threatening smoke but then we saw Kenora 20 blow up in size and run 20 km in a night. We saw evacuations and travel restrictions as the skies were filled with smoke.
Why did we have such a severe early spring fire season?
The factors that caused this included a lack of rainfall or precipitation. Beyond a freak May snowstorm and the occasional few millimetres of rain, the region didn’t get that heavy rainfall that trees are able to fortify themselves with. Moisture or humidity gives the forest life and provides a kind of protection known as a humidity or moisture dome to the forest. This turns the dry undergrowth and trees from winter into a vibrant eco structure that doesn’t burn easily. This never really happened until late June.
Kenora is on the Canadian Shield and most of us can see the rock around us peeking up through the soil. Many areas are not deep rich layers of soil over the rock. This causes them to dry out, becoming more vulnerable to fire from lack of moisture. The fire crew leaders were well aware of this factor as they fought those early May fires. Fire can burrow into the roots of trees and vegetation based on heat transfer. That causes the need for infrared scans by drones and satellites at night to see the heat. Crews stay on fires looking for smoke coming up from the ground for days. Ken17 was detected and handled on a Monday, but the crew stayed until Saturday to ensure it was out with 24 hours of no smoke. That changes the techniques and the guidelines for fighting a fire.
Heat transfer
Heat from fire transfers or moves in three ways.
- Radiant heat is where the heat travels in basically all directions from a fire source, radiating outward. This is how radiators work to heat homes. Safety tip: Don’t have anything flammable too close to a heat source as over time it will heat it up until it can burn.
- Convection heat is that heat rises and therefore you have an increased amount of heat energy going up. This causes smoke to rise. Safety tip: Don’t store dish towels or flammable items over the stove in the shelves. During a grease fire on the stove, these items can be superheated and auto-ignite.
- Conduction heat is heat that travels through something, usually metal or rock that isn’t easy to burn. Metal potholders and spoons heat up as you cook. Safety tip: Watch for metal transferring heat away from heat sources. Items around the fire can become burn hazards.
Why it took a long time to call Kenora 20 out
Let’s look again at the science. The convection heat rises but it was able to create very intense burns and flames. That intense heat then radiates in all directions including the ground. Add the intense heat travelling into that Canadian Shield rock downward, the fire has an opportunity to burrow into the very dry ground and attack the roots of trees. That dry soil works as insulation, so the burning roots and heated rock don’t lose that intense heat. That heat can slow burn the roots as embers, weakening the trees. A weakened tree will then fall over with a strong wind in a storm, exposing that ember or heat to a rich oxygen supply. Those same strong winds blow those embers into reigniting as flames or auto igniting. This is why fire fighters look for the smoke or use devices to see the heat. Then they need to break it up in controlled conditions, taking lots of time and care to get them all.
On Kenora 20, the fire crews were left overnight in areas looking for smoke. In the morning, they would receive GPS coordinates of hot spots from the drones the night before. The crews would work the areas until they were sure they didn’t leave any fires or hot spots behind them. Once they cleared an area, they would move their hose lines forward to support more efforts and make new helipads in those areas before starting the process again. This is a slow deliberate process both for safety of the fire crews and to eliminate progress of the fire.
Moisture/humidity dome
The term “value protection” changed to “structural protection” as this season had a high amount of structural loss so early. The way to counter structural loss is the moisture or humidity dome around those structures. The moisture dome is created by those sprinklers you see on the top of structures run by pumps. The early days of Kenora 20 was not a lot of direct fire fighting but sending out crews ahead of the fire to put up structural protection to create those moisture domes and protect buildings. Why does it work and how does it help fight the fire?
Fire only burns the surface of material. This requires heat energy to get those surfaces to certain temperatures. The first temperature is the flashover temperature. This is when the material is heated enough to burn but needs an ignition source to burn. Due to how heat travels, it would ignite the majority of the material with this. Secondly, it is the auto ignition temperature which is the temperature that material will ignite without an ignition source. This usually occurs when something is super-heated without flame possible. An example would be those dish towels superheated by a grease fire on stove. The grease creates so much smoke without flame that it chokes the oxygen out without igniting into flame. Once the dish towels receive enough oxygen, they burst into flame without an ignition source. These temperatures can vary due to different factors.
The flashover temperature is important as that is when material begins to burn and in a forest fire, we have an ignition source available. One factor that can increase that temperature or require more heat energy is moisture. Remember that changing water to vapour requires more heat energy than just raising the temperature. That moisture works like an armour that has to be removed before the material can reach a temperature to flashover or auto ignite. The moisture dome feeds moisture into the material and area so it can be absorbed building that armour. The sun and fire tear down that moisture from the material, making it more able to burn. Persistent heat over time can also lower the flashover temperature like carbon paper or other quick fire starters. Think of the attic fire from the heat of an incandescent bulb over years or decades left on.
Auto ignition temperatures can be reached as some trees burn underground. They only need the introduction of more oxygen to ignite from their very insulated spots under the soil. As the roots weaken from being burnt, a mighty wind pushes the tree over, introducing that oxygen with winds to start a fire anew. That ember heats up and flames auto ignite. This is why the IR scans are of importance. It tells the crews where to dig and then douse with water to cool everything down. All this takes time, manpower, and the latest technology. It makes it harder and longer to put some fires down.
The moisture or humidity of the forest for Kenora20 was reduced by that extremely warm beginning of May. The lack of precipitation didn’t replenish the moisture. These conditions along with winds, set up the ideal conditions for that horrible run of flames. It was obvious that the trees hadn’t received enough rain and were not ready to protect themselves with their moisture armour. MNRF crews put up structural protection to artificially protect buildings with moisture. That moisture slowed the fire down and caused it to bypass some structures, saving buildings. Some structures had metal roofs or other aspects that are harder to burn or with higher flashover temperatures, saving them. Others had very few trees around them, reducing the fire load or radiant heat produced, again, saving them. Many factors can contribute to what burns or not. Moisture is just one.
Hopefully this helps people understand why Kenora 20 took so long to be called out. We have to rely on nature to give us that moisture to end fires. We as humans can artificially pump out a lot of water, but those fires became larger than our capacity very quickly. Fire can also go to ground requiring yet more water and moisture. It is a complex task to put out a forest fire with these added complications.
The Kenora region is lucky to have very skilled and knowledgeable MNRF crews and leadership to take on these tasks. This fire season, we saw extra diligence and caution that slowed the changing of evacuation and fire statuses with due cause. It is far better to error on the side of caution that to unnecessarily risk greater dangers to life and property.
Robert Creedon has degrees in Criminal Justice, Sociology, and Fire Science. He has served as a volunteer firefighter and fire educator for over a decade, including four years as Minaki fire chief.