Temperatures are set to plunge as low as minus two degrees Celsius in parts of Yorkshire this week and icy Arctic blasts are set to bring the coldest winter for five years.
West Yorkshire Police has warned motorists that temperatures are set to plunge - and the risks associated with de-icing your car.
A spokesman said: "It's going to be -3 degrees overnight so please refrain from starting the car and leaving it running whilst you have your breakfast. This is just inviting criminals to steal your car. Get the de icer out or get scraping!"
Police chiefs have previously warned motorists NOT to leave vehicles unattended with the engine running while de-icing the windscreen - after a spate of thefts in the last few years.
Vehicles have been driven off by thieves who struck while motorists were keeping warm in their homes while their cars were left running outside to defrost after temperatures plummeted.
South Yorkshire Police and West Yorkshire Police have previously said unattended cars with their engines running were "enticing thieves".
SYP Roads Policing Inspector Craig Clifton said: "It may be tempting to leave your vehicle unattended allowing it to defrost before starting your journey but this makes the car vulnerable to being stolen, particularly with exhaust fumes coming from standing vehicles in the cold weather making these vehicles more identifiable.
"You don't only run the risk of your vehicle being stolen but you may also loose the right to make an insurance claim because leaving the keys in the ignition could invalidate your insurance.
"Plan your journey with extra time to safely defrost your vehicle while you are there with it."