Firefighters made the scene safe after a tree fell across the roadway and on to a car on Catlins Lane in Eastcote.
One man was treated on scene by London Ambulance Service crews after suffering from shock.
Sub Officer Chris Secrett, who was at the scene, said: “We were called after a tree had fallen down into the road, taking down a telephone wire and one of the branches went through the windscreen of a car.
“Thankfully, the man inside the car was not seriously hurt. The road was closed whilst crews worked with a local authority tree surgeon to remove the tree and make sure the scene was safe.”
The Brigade was called at 1604 and the incident was over for firefighters by 1715. One fire engine from Harrow fire station attended the scene.