Police are beefing up patrols in Watford ahead of a traditional rise in vehicle crime in the town.
Hertfordshire Constabulary said January usually sees a spike in thefts from cars including valuable parts and items left in them.
The force said in December, 29 incidents took place. Of these, 14 car parts were stolen, including number plates, windscreen wipers, spare wheels and wing mirrors. The other thefts were from vehicles which were left insecure or had a window smashed.
Detective Sergeant Paul Perkins from the Local Crime Unit in Watford said: "We generally see a rise in thefts from cars and vans during January, and whilst we are working to prevent this, we’re also asking people to be aware and take steps to prevent becoming a victim.
"We’ll be conducting extra plain clothed and high visibility patrols in the areas which have been found to be prone to incidents previously, but we’d also ask people to be vigilant too and contact police if they see any suspicious behaviour. If you believe you witness suspicious behaviour contact police via the Herts Police non-emergency number 101, or if you suspect a crime is in progress dial 999."
Police are urging people not to leave valuables, such as sat navs, sunglasses or loose change, in their vehicles, particularly overnight, which is when the thefts mainly happen.
Paul Perkins added: "We’d ask people to completely remove valuables as the offenders will still break in just to look in the glove box. It is also advisable to leave your glove box open to prevent the opportunist thieves from breaking in. We’d also ask people to ensure their vehicle is left locked and secure as we do see incidents where the offender has simply opened the door and helped themself."