Sun-loving householders are leaving the door open to criminals.
Nearly half the 35 house burglaries in the Keighley police division in the past week have been sneak-ins.
Thieves have entered houses while people have been sunbathing or working around the home or garden.
Cash and goods, ranging from wallets and handbags to mobile phones, have been stolen.
Incidents have taken place at various locations across the district including Knowle Park, Woodhouse and Haworth.
Now police are warning people to keep doors shut and locked, even when they are in the house.
Det Chief Insp Roger Gasson, head of Keighley CID, said: "The number of sneak-in burglaries has been extremely high and it is down to the fine weather.
"People leave their door open while they are in the garden or doing something in the house. It only takes a moment for someone to be in and out of your home with property snatched from a worktop.
"We would urge householders to keep their doors closed and locked."
Despite the spate of sneak-in thefts, police in Keighley are continuing to make major headway in the fight against crime.
A massive five-day blitz, which ended at midnight on Monday, has been hailed as a huge success.
The special operation, part of the Target initiative, involved more than 30 officers including members of the headquarters task force and special constables.
Addresses were raided, high-visibility patrols staged in hotspot areas, CCTV surveillance and vehicle checks carried out, and a specially trained drugs-detection dog brought in.
Dozens of people were arrested in connection with a range of alleged offences and a quantity of property and drugs seized.
Det Chief Insp Gasson said: "The initiative made a significant impact and I am very pleased with how it went. We have addressed a variety of priority crimes and recovered a sizeable amount of property. It is certainly our intention to repeat the operation."
He said police would like to hear from anyone with information about burglaries or stolen property. They should get in touch by phoning 01535 617083 or Crimestoppers, anonymously, on 0800 555111."
Areas singled out for high-visibility patrols during the operation included Knowle Park, Lawkholme, Haworth, Eastwood, and the Malsis Road/Victoria Road district.
The blitz was launched as part of a massive initiative covering all five police districts in West Yorkshire.
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