Lincolnshire Police are urging Lincoln residents to lock their doors and windows at night after the first sneak-in burglary in the city since the warmer weather arrived.
The warning comes after a sneak-in burglary on Doddington Road on May 7 between 3pm and 5pm.
The offender got in through an unlocked back door, and stole a 26-inch Toshiba TV while the occupant slept.
When the weather warms up, people open windows and doors, but leave them unlocked at night or when they are in the garden.
Officers say this leads to a spike in burglaries over the summer months, as thieves know residents will do this.
Police advise locking all doors and downstairs windows at night and even lock them during the day if you are spending time in the garden or upstairs.
Police are also reminding students or those in shared accommodation not to leave doors unlocked for housemates who are out late at night.
To report burglaries or give information regarding burglaries, call 101 or Crimestoppers on 0800 555 111.