In the last twenty years, roughly 75% of the contiguous US has been in a drought at least 10% of the time. Temperatures are rising across the country, even in higher latitudes like the Northeast. A warmer atmosphere holds more moisture, meaning that precipitation comes more often and more heavily. However, evaporation also increases as the atmosphere can absorb more water from the surface. This dries out soil and vegetation, intensifying drought conditions, and encouraging wildfires to take hold.
These warmer conditions also mean that winters are becoming milder and producing much less snow. In places like the West, mountainous snowpack and their yearly freezing and melting provide much of the surface water and moisture throughout the area. As less snow builds back the snowpack, less water is delivered to the watershed below. Scientists warn that as this continues, shorter periods of snow cover will increase the length of fire seasons in other parts of the country.
Wildfire risk is a holistic equation, affected by ambient temperature, soil moisture, and the presence and quality of trees, shrubs, and other potential fuel. As temperatures and evaporation increases across the country, dirt and organic matters dry out in turn. This provides ample fuel and room to spread for a hungry fire. Between 1984 and 2015, alongside rising temperatures, the annual number of large fires has nearly doubled in the United States. The wildfire season is becoming longer as Springs become warmer, and the driest parts of the Summer lengthen as well. Not only are wildfires becoming more common, but they are also becoming more dangerous. As the ground and vegetation dries up, fires burn hotter and faster.
