Mine was also dependant on ambient temperature, but it always seemed to squeak, just more or less at times. The problem with using silicone spray is that the squeaking is behind the wiper cowl at the base of the windshield, so you have to pull it off to gain access to where you need to spray. The dealer said that they remove the tabs when a customer has this problem so I just did it myself and saved the labor fees. They mentioned having to remove the hood(bonnet)as well but if you are patient the cowl can be removed without having to remove the hood. The vehicle has been squeak free ever since doing this.