Summer scents are usually lighter, like day scents because it is warmer, you are outside, and in the sun. Warm weather typically does not mix well with the heavier, scents with dark, rich notes. Orientals are a prefect example of what you wouldn't want to wear because they can be cloying and suffocate you(not literally).
Winter is for warm scents because it is cool and something crisp and clean smelling is just not as appealing. Warm vanilla and sandalwood combinations are my favorite for winter. The air is less humid in winter because of the air temperature and warm scents seem to travel well in that dry air.
It is preference, not law that these ideals are laid out. Most people go for what I just stated, but everyone is different. I hope this helps.