We planted a couple of young carob
trees last year and they seem to cope with our frosts. We are in a Mediterranean climate with hot, dry summers, but the winters are 'cool and wet', which, in our case, seems to mean weeks of rain interspersed with drier weather with frosts down to minus 5C. Some winters we go much colder minus 9 on occasion, but we didn't have the carob planted then so we're not sure if they would have survived it or not.