WASHINGTON – Summer brings changes in behavior as crowds head out to enjoy the season, and thieves take advantage.

Criminals hunt for scores during pleasant temperatures, searching for cars that may be easy targets.

“Over 50 percent of Montgomery County cases involve an unlocked vehicle,” said Officer Rebecca Innocenti with Montgomery County Police.

“But during the summer months people are also leaving their windows down.”

Authorities urge drivers to take precautions, lock up and leave valuables at home.

Homeowners who will go away on vacation also are encouraged to be proactive.

“You don’t want to close up your house and make it look like no one is living there,” Innocenti said.

“Suspects perhaps notice if you are not getting mail picked up or if you are leaving newspapers out front.”

A neighbor or friend can be of assistance, maintaining the property while the owner is away.

“Ask them to walk around your home on a daily basis. Check to make sure your windows are secure and your doors are secure,” Innocenti said.

Securing sheds and garages can help prevent crime. Police say they are frequent targets.

“We just want people to be mindful. Take precautions to avoid these crimes,” Innocenti said.

Follow @WTOP on Twitter.