Summer usually brings hot, dry weather and elevated wildfire risk to the western United States. Summer 2015 was no exception. As of August 17, outbreaks of large wildfires had charred nearly 7 million acres, nearly two million more than the ten-year average through mid-August.

While 73 percent of the burned area is the result of massive fires in remote forests in Alaska, large blazes have emerged in the Pacific Northwest as well. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite collected this image of several fires burning in Idaho, Oregon, and Washington on August 16, 2015. Red outlines indicate hot spots where the sensor detected unusually warm surface temperatures generally associated with fires. Thick plumes of smoke drifted from the hot spots. The lower image shows the same fires on August 13.

Two of the most destructive blazes, the Canyon Creek Complex and Cornet–Windy Ridge fire had burned about 136,000 acres (55,000 hectares, or 200 square miles) and destroyed 47 structures as of August 17.

Many of the fires were triggered by lightning strikes, but years of drought have parched forests in the West and primed them to burn. A recently published analysis of 35 years of meteorological data found that many parts of the West face longer wildfire seasons than they did a few decades ago, likely because of climate change.

NASA image courtesy of LANCE/EOSDIS Rapid Response. Caption by Adam Voiland.