One advantage of summertime at least in Holland is less traffic and no traffic jams :)
Currently I am involved in designing a conceptual data model using ORM (= object role modelling). Very interesting material and nice model for data modelling.
ORM can be used to build information models that are consistent and unambiguous because ORM is based on first order predicate logic. (source: ORM Foundation)
For data migration and integration it is important to know what objects mean and how they are used in other systems. In project it is wise to have dictionary available were object are describes and also their relations. I cannot count the times people were talking about their ideas and at the end they were talking about exactly the same.
ORM helps to clarify meaning When you create an object-role model you are creating a precise and meaningful description of your information domain. So ORM tools provide a means for people to agree on exactly what they mean. (source: ORM Foundation)
If you would like to read more you can check the ORM Foundation website. I am currently also reading 'Information Modeling and Relational Databases: From Conceptual Analysis to Logical Design' by Terry Halpin and Tony Morgan.