It has been cold this month, as everyone knows, and this can create an environment for crime, the Prince George’s County police said this week.

At a news conference on Tuesday, the police addressed car theft, which is aided when motorists make understandable efforts to warm up their vehicles before driving them in the early morning cold.

“People have been leaving their keys in cars,” said Cpl. Maria McKinney, a police spokeswoman. Leaving the car unattended while the motor is running and keys are in the ignition offers “a prime opportunity for someone to pass by and hop in,” she said.

Police said car thefts are down this year in the county but could be lower still “if drivers stopped” letting the car run with keys inside.

Also a problem, of course, is how spring has dragged its feet. Wednesday was a bit warmer than its predecessors, but the morning temperature was nevertheless in the 30s. The morning low tem­perature, as measured at Reagan National Airport, has not been above 39 degrees since March 16.