In the movies, Paris is famous for having lovers kiss in the rain. Since it rains often in Paris, it's likely it was raining the day they were filming the movies and the shots looked good anyway. During the fall and winter, the rain is chilly, and the wind makes using an umbrella rather pointless. In the spring, there are random downpours, where the streets are practically flooded, and yet the rain manages to stop in an hour or so. There is an amusing realization when, walking down the Champs-Elysées, it begins raining and everyone within two feet of you pulls out an umbrella. It's a wonder these people are so prepared, until the people walking around selling umbrellas are noticed.
There is nothing like summertime in Paris. The weather is warm, all the people are out strolling along, and the day's agenda consists of lounging about on the grass. Sometimes, the weather can be really hot, but usually it stays nice for quite a while and is enjoyable even after running errands. The nice weather also brings the tourists to Paris, which can make gathering places and transportation vehicles a bit too crowded.