Avignon Bridge with Popes Palace and Rhone river at sunrise, Pont Saint-Benezet, Provence, France

As the only major European river that ends in the Mediterranean -- the Rhine River empties into the North Sea and the Danube River into the Black Sea -- this ravishing French waterway shares many characteristics with that sunny sea's warm, scented shores.

The Rhone river cruise season stretches from March until December, taking a break in January and February. Southern France is at its most gloriously sunny in the summer months (June to late September). Here's what to expect, weather-wise, throughout the year:

March, April and May: The biggest thing to know about the Rhone region is that its proximity to the Mediterranean means even late spring and autumn can be balmy, provided the Mistral does not blow fiercly.

This wind -- whose name means 'Master', as the locals believe it can master their moods and make them depressed or irritable -- funnels down the Rhone Valley from the Swiss Alps. It can make the river both chilly and choppy, reaching up to 95 miles an hour as it streams toward the French Riviera and the Gulf of Lyon.

In the winter months, the Mistral can blow for weeks at a time, and its icy flow can seem never-ending, but it can also strike in the spring. In Provence, it blows an average of 100 days in every year. Pack a warm jacket, just in case. Strong winds rarely cause a river cruise to cancel, but it has been known to happen.

The spring snow melt in the Alps also brings with it the possibility of flooding, which can impact locks and bridges on the Rhone. If that happens, river cruise lines will bring passengers to different towns by bus, instead of sailing.

June, July, August and late September: The south of France is gorgeous this time of year, with hot temperatures and sunny skies. Keep in mind that in August, many French go on vacation, and they head to this area of their own country; crowds are common. In September, the grape harvest begins -- an event called Vendanges -- and the towns along the Rhone are likely to have wine festivals. 

October and November: These months are when the region receives the most rain. However, the cloudbursts are usually short, and there's still quite a bit of sunshine.

Late November and December: Cities along the Rhone -- including Lyon, Avignon and Marseilles -- do have Christmas markets, and a handful of lines offer sailings to see them. Expect the temperatures to drop below freezing, although actual snowfall is unlikely. The Mistral is at its worst at this point, so definitely bundle up.