Autumn road trip in France (1 month)

I’d start in the north and head south for possibly better weather? Just my thought.

If you want to optimize the weather, then definitely (as in most places in the northern hemisphere) start in the north and work your way south. If you want shorter daylight hours and colder(possibly rainier) weather while touring the northern parts of France, then start in Nice.

Another vote for North to South

Historical averages indicate Colmar by late Nov., will have highs in the 40s(F) and near freezing overnight
At that time Nice will be 10-15F warmer than Colmar

Another vote for North to South. We took the RS Loire to the South of France Tour a number of years ago ending in Nice. It was Fall and the weather was lovely the entire trip. Don’t blame you for wanting a warmer climate. We live in WA State & appreciate above 55 degrees as well.

What a nice way to see FR. I agree with the others about starting in the north and driving south. Have you considered visiting the Alsace region and Burgundy when you visit the alps? New York has nonstop flights via Nice.
A lot of people will disagree with this, but you can pick up a car at the airport and drive to Honfluer (2h 15m) and sleep there one night before moving on. If you’re uncomfortable driving the day you arrive then don’t. After you finish touring the Normandy region, drive to Ambiose (3h 45m) and make that your home base in the Loire Valley. I was in Ambiose in 2012 and had the best FR onion soup at Anne de Bretagne (not sure if it’s still open). What made it so good was the broth and my sister agreed.
As you drive towards Carcassone you may want to stop in the Dordogne department i.e. St-Emilion (4h and good for wine drinkers) and then to Sarlat (2h). Carcassone is another 3h 15m from Sarlat.

You are getting good advice. Your basic choice in doing the east side (Colmar, Lyon, Burgundy, Provence, Carcassone) or the west (Normandy, Loire, Dordogne, Carcassone). It would be easier to incorporate the east side in a later Alpine trip if that is your future plan. But north to south is the answer.

But north to south is the answer.

Not so fast. If the objective is to catch a bit of warmer weather, I would start where you have the best chance of warmer weather - Nice in October. Not really wanting to make weather predictions, average temps are available online and you´ll notice that the best chance for any warm weather, averaging from around 21º (70F) to 18º (64F) will be Nice in October. If your objective is to average out lower temperatures, then north to south is the answer.

Given the small latitude difference between the Paris and Nice, there will be no discernible effect on available daylight which, within just a few weeks of the shortest day of the year, will not be plentiful. Expect darkness near 17h00 (5pm) and minimal daylight hours in which to explore. Being Canadian, you probably already know about short winter days but France is potentially even farther north, Paris itself being 48°N.

Carcassonne takes you quite a distance west and increases travel time just to see one location. Consider instead the walled city of Aigues Mortes southeast of Montpellier, which I find just as interesting with fewer crowds though I shouldn´t expect crowds thsi time of year. This better positions you for A750/A75 northbound which is the only free autoroute in France, free except for a 5€ charge to cross the Millau Viaduct which itself is a worthwhile destination. There are a lot of places to visit just off A75: Laguiole (for the knives), Aubrac (for Aligot), St Flour, but just before St Flour is the Garabit viaduct with a wonderful hotel restaurant le Beau Site. The viaduct was built for trains by Gustave Eiffel. It´s a horizontal Eiffel Tower, illuminated at night, and a fabulous hidden gem.

I simply mention this portion of north/south travel because many people overlook it and, no matter which direction you travel, it is an amazing part of France.

Thank you so much for the thoughtful advice everyone! Taking it all into consideration we’ve decided North to South is probably the best for constantly decent weather.

We do hope to see more of the Dragone region ( I hiked through here from Le Puy en Velay to spain on the Chemin de St Jacques in 2009 and it was stunning!) in the east and now that we going North to south and back up again Burgundy and the Alsace region will fit better into our plan. Ahh, it will be so nice to travel again!