A sleeveless jersey with a lightweight light sand color soft sweater with tan wedges, for any chilly air conditioning, or at night. I would carry a cute tote in this color too.
France is hot, but you could wear skater dresses! Like one of these in the picture. These are from charlotterusse.com :)
might be a bit too hot for that, France in July can be 30C easily somedays may be cooler but nothing below 20C