In the past month there have been 35 overnight thefts from unattended vehicles, with thieves breaking into vans and stealing power tools inside.
The Bilton, Jennyfields and Knaresborough Road areas of Harrogate have all been hit and North Yorkshire Police say owners should be "extra vigilant."
Temporary Detective Sergeant Tom Barker of Harrogate Investigation Hub said: “Although additional policing resource has been deployed to these areas to deter and disrupt criminals targeting these neighbourhoods, I would encourage residents to be extra vigilant at this time.
"It is advisable to remove any valuables items, such as expensive tools or sat nav devices, from your vehicles overnight, to avoid them becoming a potential target and always ensure your vehicle is locked and parked somewhere secure."
Det Sgt Barker said anyone who saw suspicious activity should call 999, or 101, to report something which had already taken place.