10 major wildfires continue to burn in California, with several more in Oregon and Washington.
Some have been caused by lightning, others by people, which according to Mark Schwartz, director of the UC Davis John Muir Institute of the Environment, is happening more often.
The San Diego fires in May WERE caused by arson. Humans are also to blame for the recent Bully Fire in Shasta County and the Sand Fire in El Dorado and Amador counties when hot exhaust pipes torched dry grassland.
A campfire in the Sierra National Forest ignited the French Fire burning east of Modesto.
And after a year-long investigation, a bow hunter has been charged with letting a campfire get out of control, sparking the largest wildfire ever in the Sierra Nevada, the 250,000 acre Rim Fire.
According to the California Department of Forestry and Fire Protection, or CAL FIRE, seven of the largest wildfires in California historywere human caused.
With a long fire season ahead, CAL FIRE has launched an educational campaign called One Less Spark to help prevent human related wildfires. It covers campfire safety, equipment operation, debris burning and vehicle maintenance.
Northern and Central California are of particular concern. See the Fuels and Fire Behavior Advisories map.
Explore further: Fire season in West expected to get more intense