I have been planning a trip to Provence in October (4-12). I am about to book the flight and I just saw that October has the most rainfall of any month! I checked Nice and Marseilles. Anyone have anecdotal evidence that this is not an issue?
My wife and I traveled to Nice and on to Provence at that same time a few years back and the weather was terrific. As I recall the first week of October we were in Nice and it was in the high 70s Fahrenheit. We drove throughout Provence and settled into Vaison-la-Romaine for a few days and it was still in the upper 60s and lower 70s. When we moved onto Beaune and later Paris it was later in October. The weather had become more gray and wet but we still had a fantastic time. With all that, keep in mind that one year may vary from another. If I was in your shoes I would book that flight and go.
We were also in Provence and stayed in the Luberon in October of 2011. It had been cloudy with warm temperatures but during one night, the wind switched. The next morning, the sky was bright blue but the nights were cooler and the days a bit more brisk. Layers as always. Light sweaters and jackets in the morning and evening.