I don't know sites other than the usual Yahoo weather or Météo France (http://www.meteofrance.com/), but we go to France every fall around the end of Sept and into Oct. The weather is usually warm during the day (atleast it is in the Pyrenees -- around 60 - to high 70's -- depending on the weather pattern) and it cools to the 50's or lower at night. I know this isn't much of a help - but you can usually expect some good weather this time of year.

Regards, Susie Newton, MA