Cold weather in Medford last month meant more hot cars.
Police say residents were leaving their cars idling unoccupied in the driveway or on the street to warm them up, prey for thieves.
The Medford Mail Tribune reports that the number of vehicle thefts nearly doubled, when compared to the previous December: 27 this year, 14 last year.
Lt. Mike Budreau, the police spokesman, says the spike in thefts is probably the work of one or two people just using the vehicles for transportation. He says the vehicles aren't being dismantled for parts, and are generally recovered in a week or two.
No suspects have been identified.