Police chiefs in South Yorkshire are warning of thieves prowling the streets looking for open doors and windows as the weather improves.
They are warning that crooks will take advantage of the improving weather and look for homes with poor security.
A South Yorkshire Police spokesman said: "With spring on the way and the hopeful return of warm weather, people will start to spend more time in their garden.
"Traditionally, as the weather improves and becomes warmer, householders leave doors and windows open to provide ventilation. People will spend more time sat outside and some will not lock their front doors.
"Unscrupulous thieves will also take advantage of the good weather, but they will take advantage of people who unfortunately fail to secure their homes. "Sneak-in burglaries will increase over the spring and summer months with thieves simply walking into houses that have been left insecure.
"Please do not become a victim of a sneak-in burglary - secure your house if you go out into the rear garden and remember to shut and lock the windows in any room in which you are not sitting."