Tree experts say they haven't seen such conditions since the late 1980s and 1990s when entire hillsides of forest trees were wiped out.
The low rainfall over the last few years has left trees vulnerable to a surge in bark beetles.
Experts say when there's sufficient moisture, trees are healthy and they're able to fight off beetles.
But when they're stressed by drought, they're less able to defend themselves so beetles thrive.
The beetles bore into the tree bark and lay eggs. When the eggs hatch, the grubs burrow into the tree and feed off the tree.
That cuts the tree's supply to water and nutrients and eventually the tree dies.
Experts say forest thinning and replanting of healthy trees could help, but with severe drought, there's little that can be done.
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