The state Department of Transportation says a tree on the slope above Pali Highway in the Kailua-bound direction has fallen.
The tree, which fell just past the tunnels, is not currently blocking any lanes. Officials say weather may have been a factor.
However, at 7 p.m. Monday, crews will close the right-hand lane to remove the tree. Work should be completed by 10 p.m.
Motorists are urged to drive with caution.