A lethal combination of drought, heat and voracious bark beetles has killed 26 million trees in the Sierra Nevada over the last eight months — an alarming finding for a state already raging with wildfires fueled by desiccated landscapes.

The dire estimate offered Wednesday by federal officials brings the loss of trees since 2010 to at least 66 million, a number that is expected to increase considerably throughout the year, despite an average winter of rain and snow that brought some relief to urban Californians.