Worst hit areas were the CBD, Kuripuni, the area near Queen Elizabeth Park and the Renall and Cornwall St area where commuters parked.
About 60 per cent of all theft from cars occurred in Masterton, which has about 16,600 registered vehicles.
Thieves were targeting small, desirable, easily concealed items like iPods and iPads.
Mr Crawley said it was unclear what had caused the increase, but it might be due to drivers being complacent.
"Maybe there's an opportunity for easy targets."
The increase was a district-wide trend with Wellington also reporting more thefts from cars, Mr Crawley said.
"It's not just little old Masterton."
People needed to make sure they locked their vehicles, did not leave things in their cars and thought about where they parked.
"Why park in a dark area when you could park 300m down the road under a light - it may not stop them but it does make it harder."
People needed to be vigilant about reporting anything suspicious.
"People may not think it's important but it may actually lead to us catching up with people who are doing this."
"We do need people to report in and if they have something taken then they do need to tell us because it does all paint a picture."
Police would be working with partners such as Neighbourhood Support to raise public awareness, Mr Crawley said.
"[We] will probably end up doing pamphlet drops around carparks and obviously increasing our patrols for areas that are high risk - but ultimately, we can't solve this problem alone."