What to wear in France during October

Layers and rain gear. And the all-important sturdy, comfortable shoes. You are very likely to be dealing with some wet cobblestones.

Make that "non-slip tread walking shoes"...
A raincoat with a hood is a good idea, because it will be windy in October, and umbrellas are virtually useless.
Light layers, unless you are very cold-natured, would be best.
And I would sneak in a t-shirt and a pair of knee-length shorts, just in case.

Good ideas from other posters. Layers are best; I pack mostly short sleeved shirts, a couple long sleeved that can fit over the short sleeved (button down collared for example). In fall I use a thick fleece, SCOTTeVEST Chloe and my raincoat fits over that. I take a thick wide scarf and light ones. I also pack a thin pair of gloves, sometimes the cheap dollar store minimitts.

Enjoy France!

A good rain shell that's waterproof and longer than a jacket (so the rain drips past your bottom), with hood, and covered zippers. I'd expect some rain, possibly with wind, in Normandy - unless you get lucky.

Shoes should be comfortable with non-slip soles and at least somewhat water resistant. Add wool socks, they don't have to be really heavy but wool performs when wet - cotton doesn't (at least pack something non-cotton). I'd also opt for quick drying socks rather than thick socks.

I'd go for pants that dry quickly, jeans dry very slowly.

Do warmth with layers, a sweater or two that can be layered over your shirt - under your rainshell - when it's cold or wet, but can also be worn with just a shirt when it's a cool/dry evening.

I think it will be relatively comfortable in Arles, so don't overdo it with warm things.

We often are in Paris in October and usually wear jeans and a lightweight jacket with a sweater underneath if needed. The weather for us the last couple of years has been largely sunny and pleasant and cool. It is a wonderful time to travel to France. In the south it may be warmer so that a lightweight shirt is enough of a jacket. Always have rain gear for the showers, but recently we have not seen much of that.

I agree with Janet....October is our favorite month to travel in France...weather is usually lovely. We do take rain gear , but have generally had sunny cool days.

Note that last year in mid-September in Paris a few days of low temperature forced me to buy a thin pair of gloves in Monoprix, which of course was the signal for the sun to come out and warm things up. But be prepared.

For an older man, it is easy. I take a wool blazer, cashmere sweater, North Face jacket with hood, mid-weight wool trousers and French wool scarf (2 meters long). (You can buy the scarf there at a men's store.) We have traveled in most parts of France from mid-September to mid-October, and I have never been uncomfortable.