While some days might be very cold and wet, the others are still warm and cozy. Aesthetes and romantics will definitely enjoy probably the finest light of the year during autumn. This means that the season of warm hues might be the best time for wandering around the city. Especially in wonderful Parisian parks and gardens.
The first one not to miss is Le Jardin du Luxembourg, huge and very famous park with big old trees, cosy alleys, chairs which you can move where you like and playground for ping-pong, badminton and, of course, boules. In early autumn you'll even see some palm trees in large wooden pots. One of the main attractions of the park is also the beautiful fountain of Maria Medici.
Another picturesque place is the Square Jean XXIII behind Notre-Dame de Paris. This pleasant spot is perfect for taking a break for a snack while admiring the gothic cathedral beneath the trees in full autumnal foliage. The best time to go there is either early morning or evening otherwise, you'll find dozens of tourists and no free benches.
In the middle of the noisy le Marais you'll find a charming garden inside the Carnavalet museum. This inner courtyard with carefully cut bushes is open and accessible to anyone, you just have to go through the museum where the entry is also free. But this place is so cosy and beautiful you want to spend here at least all day drinking coffee and reading a book.
The garden next to Auguste Rodin museum is also amazing during autumn. In fact, the beauty of the sculptures is emphasized by the hues of the leaves and the special atmosphere. Visit this garden if you want to sit back and fully enjoy fine art in such a poetic background.