I have seen posts about river cruises being disrupted by water levels (too high in spring and too low in summer) and passengers being moved around by bus and having to stay in hotels instead. I am looking at a Rhine river cruise and am wondering when is the best time of year to go to avoid this situation.

I can't answer your question re: water levels, but I can throw another clod in the churn. IMO one of best times to go on a Rhine river cruise is in early December when nearly every stop has delightful Christmas markets. Color and festivity everywhere. We enjoyed our Viking cruise called Rhine Getaway in early December last year immeasurably. (And we experienced no water level problems for what that's worth--no guarantees about whether that was standard or exceptional though.

jasper02:
there is no way to out guess the weather although it's safe to say Spring rains can cause issues such as you mention above. My humble opinion would be late October or early April and hope for cool, temperate conditions. I've cruised during both these months and had no issues with water levels in The Netherlands/Belgium or on France waterways.

I recently returned from a week long Rhine River cruise, Basel to Amsterdam, concluding in mid May, my fifth such river cruise experience. Unfortunately for my metabolism, there were heat wave conditions with 80 degree temperatures, much too warm for the walking tours for me which caused swelling of my ankles and feet. It would depend on what your comfort level is, whether you prefer cool or warm. I'd base my choice on that.

Of course, there is the choice of doing only one of the walking tours per day, either morning or afternoon and enjoying sitting up on the sun deck or reading in the lounge. The hard part is making that choice. I skipped one of the morning tours because I needed to rest mid cruise. It was marvelous to sit and read as we cruised to the next stopping place to pick up those who chose the tour. Our tour director emphasized the cruise was not a marathon and saving energy would make it so much more enjoyable, if not memorable!

Bon Voyage!

We have taken several river cruises in mid September and all have been wonderful. The weather has been beautiful on every trip.

The original question by the OP was about river water levels. The simple answer is that it depends on the river. The Rhine is one of the most problematic as sometimes it's too low and sometimes it's too high - both undesirable situations.We were on one of the cruises that was too low, and spent most of our time on buses. It was a Viking Cruise and I have to admit that they did a pretty good job of salvaging things. In any case, Fall is dangerous for low levels if there has been a dry summer in Switzerland and Austria, and Spring is dangerous for high levels if it has been a rainy winter. BTW, our cruise was in the fall.There are many web sites dedicated to this topic, but don't expect warnings from the cruise company. It won't happen, and in any case, you have to reserve river cruises far in advance, and the exact water level situation isn't clear until very close to the sailing date.

Below is a link to the web site I wrote about our Rhine river cruise "on wheels".

A CRUISE DOWN THE RHINE

On the other hand, don't be discouraged, Since our famous cruise on the Rhine, we have done 2 more river cruises without any problems due to river levels - the last one on the Danube only 2 weeks ago.