MINNEAPOLIS (WCCO) — It’s that time of year, when mornings are extra crisp and the urge to give your cars plenty of time to warm up is overwhelming.

But St. Paul Police are warning that it’s also the time of year when thieves are looking to make off with unattended, running vehicles.

READ MORE: Minnesota State Auditor Julie Blaha, Sen. Melisa Franzen Injured In Crash

Police said that nine cars have been stolen in the last two days after owners started the engines and then left their cars alone.

“It’s easier to steal a running, unattended car than it is to steal one that has a person in it. Please stay with your car while you’re warming it up,” the department tweeted.

MORE NEWS: Minneapolis Police, Community Groups Help Bring 18-Hour Standoff To Peaceful End

A number of vehicle experts dispute the notion that you should let your car idle for long periods of time when starting it in the dead of winter. While some have said it’s good to run it for a few minutes, even up to 5 to 10, others say that you don’t need to warm it for more than 30 seconds. The latter group says that the car’s engine will warm up faster if the car is moving.