Hi everyone,
Friends of ours are thinking of going on a river cruise in France in September. Because I plan a lot of our trips, they thought I could answer some questions, but I can't because we have not taken a river cruise. They are cruising with Avalon Waterways. The cruise begins in Paris and ends on the Cote d'Azur. They will be cruising on the Rhone and Saone Rivers. They have asked the following questions:

Are there low water level problems expected then for the Saone and Rhone Rivers? (He is concerned that Europe has been having dry summers recently.)
Is it better to cruise from north to south or vice versa? I guess they have a choice of going from Paris to Cote d'Azur or Cote d'Azur to Paris.

Thank you very much for any help and advice you can give me.

I have never taken such a cruise, but I did read someone's trip report from last year that did mention certain stops being cancelled or modified due to a low water level. Since every year is different, you never know!

maybe it needs to be reported

For this year, I would be more concerned about an overabundance of water rather than an insufficiency. Either way, I certainly do not make weather predictions.

Makes absolutely no difference.

Kerouac, that might have been me, though our problem was too high water which meant that there was not enough room for the boat to pass below certain bridges.

I honestly don't know how your friend could hope to anticipate in Jan/Feb what the water levels are going to be in September.

We cruised down the Rhone from Lyon to Avignon, which actually means going up from Lyon to Beaune, then coming back down again and sailing down via 3 or so places to Arles, and then back up again to Avignon. So although we were ostensibly going south, we also went north and it made no difference at all.

Do tell them to take a good book.

Yes, annhig, I realized that later, since the big floods last year in Paris were in June (which is extremely unusual -- the floods are normally at this time of year, which is precisely what is happening). High or low water can happen at any time, and there is no way to predict it.

Thank you everyone! Your answers are more or less what I expected because it is next to impossible to predict what weather and water levels will be in September. I promised our friends I would ask the experts, though, so I appreciate your help. I will relay your replies to them.

There is lots of information on the internet about this topic, Including here on Fodor's travel forums.
Here is one link which has some general information:

https://www.rivercruiseadvisor.com/water-levels/

We did this cruise but with Grand Circle - we did enjoy it. On our itinerary, I think the stops were a bit different depending which direction you went and that influenced our choice. Some of the towns we stopped in were a bit quiet. But your friends should be able to add a few days at each end - in Paris and in Nice - I'd encourage them to do that unless they have already spent quite a bit of time in either of those lovely cities.

The fact that there is high or low water need not spoil their enjoyment too much; the cruise companies are very good at finding other places to tie up and getting the transport organised so that excursions still go ahead, though they may not be quite as advertised. They have to appreciate that it is just possible that the one place they are desperate to see may be the one that is missed out because of high or low water.

Thanks again everyone. I will relay the information to our friend, and also suggest to him that he should ask the cruise company what their back-up plan is in case of high water levels or low water levels.

The solution is to move you by bus from hotel to hotel. At cruise prices.

The cruise critic www.cruisecritic.com has comments from people fuming about cheapo bus tours substituted for expensive river cruises. "The solution is to move you by bus from hotel to hotel. At cruise prices." The terms accompanying the bookings allow this.

This site monitors river levels: River Levels | rivercruiseinfo

We did a cruise on the Rhine with Viking.
The river level was low and we spent most of our time on buses and in hotels.

The buses were first class and the hotels were all 5 stars.
Viking did the best they could.

Thank you everyone! I just emailed our friends with a summary of your responses. And I gave them the links people included.