Weather in Paris October - November

A website like Wunderground provides historical temperature and precipitation. This is an invaluable tool for travel planning. look up Paris, go to the Calendar view, then look at the dates you are traveling for the past 5 years and see trends.
Given that most of us are tourists, our insight is limited to the few weeks we ever visit. Best to have some historical data....and it never hurts to take a waterproof jacket with layers or at least, there will most likely be folks that come out selling cheap 10E umbrellas as soon as it starts to rain.

I have spent several full Octobers in Paris and a couple of Novembers. In my experience, October has been glorious. Here was an October 31 a few years ago:
https://janettravels.wordpress.com/2011/11/01/stroll-on-a-sunny-oct-31-parc-citroen-to-the-eiffel-tower/
Generally October has been temperate, often sunny and light jacket weather -- occasionally it was warm enough for just a travel shirt as jacket. I remember one October where it literally rained only one day -- October 5 which was the day we had Eiffel Tower tickets.

I'd be in Paris every October if I could.

November in our experience has been rather dour, overcast and showery. The days are getting very short and is pretty gloomy. Most of the heavy rain was at night but it was still chilly and gray and showery.

My travel coat is a medium weight trench coat with 18 hidden pockets from Scottevest.com, and it is good for October in Paris generally. Usually I wear it just over a turtleneck but it layers well on chillier days with a lightweight down vest or a polartek. A raincoat is always useful in Paris and one that then layers well is adaptable to the weather. It is not super cold this time of year usually.

I was there at about that time and it was beautiful. I had a raincoat I used also as a windbreaker and a sweater. But, a weather app would give you better info than people's individual experiences. Look at historical weather. Also, you might start looking at a forecast about a week before you leave to help you pack

My experience with Paris in October is similar to Barbra and Janet. We experienced light sweater weather, with partly cloudy to sunny days with no rain. The leaves were turning and the city was gorgeous.

I found the temps and weather similar to when I have to travel to the Hudson River Valley in New York.

You probably need a raincoat, but not a warm winter coat. The raincoat can be used as a regular coat anyway, and you'll probably need to wear more than just a sweater at that time of the year.