Police in Chesterfield, Bolsover, North East Derbyshire and the Amber Valley are reminding motorists about vehicle security on icy mornings.
The advice comes as drivers may become tempted to leave engines running while their car warms up and the frost clears, leaving it in danger of being stolen.
Community Safety Inspector Russell Dakin said: “Although no reports have been received yet, the winter has only just started and on frosty mornings there is an increased likelihood of vehicles being stolen whilst being defrosted by their owners.
“Please don’t leave your car unlocked and with the engine running while it is defrosting, even on your own driveway, as it makes it easy for an opportunist thief and could invalidate your car insurance.”
Insp Dakin added: “You may also put your own safety at risk if you tried to stop someone from trying to steal your car in this situation, so make sure your leave enough time to properly clear your vehicle in the mornings.”
Anyone with information about car thefts should contact Derbyshire police on 101, the non emergency number, or Crimestoppers anonymously on 0800 555 111.