In Alaska, fire season starts in the spring. It's when the snow is gone and the leaves haven’t sprouted from the trees — one of the most dangerous times of the year for wildfires.

Spring danger

Most places around the country experience the greatest fire danger late in the summer. When vegetation dries out and heat, a lack of moisture and wind combine, there are ample conditions for a dangerous fire.

For Alaska, it’s a little different. Wildfire season starts April 1 and runs through Aug. 31. Alaska doesn’t typically see thunderstorms early in the year, so the danger in spring is primarily human-caused blazes.

The time between when the snow melts and the leaves return to the trees is exceptionally prone to wildfires. Snow helps cover dry grass and vegetation and, as it melts, it puts moisture back into the soil.

Spring is often dry and windy for many parts of Alaska. Once the snow is gone, rain is the only way to get moisture into the atmosphere until leaves return and grass comes back to life.

Plants return moisture to the atmosphere through evapotranspiration. Think of it as plant sweat — it helps keep the atmosphere from drying out. Dry, dormant plants fill with moisture as leaves return, making them much harder to catch on fire.

Human-caused

Dry vegetation, wind and a dry atmosphere are all ingredients for a wildfire. The only thing missing is the spark.

In the spring, the most common way to get that spark is from people. It’s easy to assume that spark comes from careless burning or out of control fires, but it takes much less than that to start a fire in the right conditions.

Relative-humidity is a way to measure the amount of moisture in the atmosphere. In the spring in Alaska, relative-humidity drops to levels as low as 10% to 20%. That’s lip-cracking dryness. In those conditions, dry grass or other vegetation can ignite from a small spark.

Something as small as a stray ember or smoldering cigarette can be enough to start a wildfire. Even a snowmachine can start a wildfire, like what we saw in the Interior earlier this year.

It's important to be extra diligent this time of year in order to prevent wildfires. Just because the leaves are out in Anchorage or Fairbanks, doesn’t mean it's that way for all of Alaska, or that fire danger is behind us. A little extra caution can go a long way.

Late season

Later in the season, the threat shifts from human-caused ignition to natural dangers. Thunderstorms and specifically lightning become a much greater danger. In fact, lightning is responsible for more burned acreage than human-caused fires not just in Alaska, but also nationally.

The amount of land burned by wildfires each year in Alaska is staggering, with population density, resources, and the type of vegetation partly to blame. In 2018, over 400,000 acres burned across Alaska. Most of that, far from any population center and more than 380,000 acres caused by lightning.

The bigger picture

Wildfires are a natural process. Without the presence of people, they would still occur all around the world.

Even though a vast majority of the land burned in Alaska each year is caused by lightning strikes far from roads or towns or people, the number of fires in the state caused by people paints a different picture.

Of the 362 wildfires in 2018, 224 of those were caused by people. Those fires tend to occur in locations closer to roads and people, meaning more resources are used to contain them before they burn out of control.

Even though the acreage might be greater, human-caused fires are much more common than fires from lightning strikes.

To help you understand how to avoid starting a wildfire, the Alaska Department of Natural Resources put together a page to help understand guidelines for each type of fire.  

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