Police believe heavy winds might have caused a tree to fall on a car, killing the driver.
Emergency services were called to the scene in Odiham, Hampshire, at 7.17am on Tuesday.
A Hampshire police spokesman said: "Officers received a report of a tree having fallen on a car on the A287 between Rye Common and Ewshot.
"The driver of the car died at the scene.
"His next of kin have been informed and are being supported by specialist officers."
Inspector Simon Hills said: "Part of the investigation will be to determine if the weather was a contributing factor.
"I am appealing for anyone with information about this incident to get in touch. If you saw what happened please call us on 101."