Paris Monsoon?!

I often get emails from people visiting Paris asking me "I'm coming in [month] what should I pack?" I never know what to reply as, in Paris, you can never tell in advance what the weather will be like. Take this early July period, for instance... In theory, it should be warm an sunny, and though we're experiencing some heavy rains. And the week to come does not look too good. Tough luck, I'm going to Brittany (Bretagne) tomorrow (Monday) to follow the Saint-Malo>Nantes stage of Le Tour de France. I'd better take my umbrella!