HALF the burglaries in Huddersfield are `sneak-ins' - helped by careless householders leaving their property unattended.
Police and insurers jointly warned homeowners to stay vigilant during hot weather.
Brazen burglars are walking straight in through the front door as people light barbecues, mow lawns or sunbathe at the back of their homes, they say.
Sgt Tim O'Sullivan of Huddersfield Police said more than half of all burglaries in the town were "sneak-in" thefts, often during the daytime.
He said windows and doors should always be secured, even if people were going out for only a few minutes.
Ground floor windows should also be locked before people retired at night.
"People should continue to be vigilant despite the current warm spell and even during the hot, sticky nights," he said.
The warning comes as home insurers Asda and RAC Insure have also warned people not to let their home security guard down during the summer.
Research by RAC Insure found that more than a quarter (28%) of burglary victims confessed to leaving their front door open and a shocking five million owned up to leaving their front door wide open after leaving the house.
Nick Hall, RAC Insure's managing director said: "With the warmer weather comes the temptation to leave windows open, even when we go out, which is like an invitation to would-be burglars."
David Rutley, ASDA's director of Financial Services said: "It's important to lock up behind you or make secure the parts of the house you can't see from your deckchair are secure."
A Home Office spokesman said: "Burglary is an opportunistic crime. It takes a burglar just five minutes to break in, steal property and leave.
"So it's important to remember to lock up your property to avoid becoming a victim."