The Middle Rhine Valley is at its best in May, June, and September. Spring brings the fresh green of the new vine growth against the slate cliffs; autumn brings the harvest, wine festivals, and golden light. Summer (July and August) is the busiest time — the river is crowded with cruise ships and the towns with tourists — but the weather is reliably warm and all services are running.
The wine harvest in September and October is the most atmospheric time to visit. Almost every village along the valley holds a Weinfest, with local producers pouring Riesling in town squares and temporary pavilions.
Winter is quiet — many restaurants and boat services close November through March — but the valley has its own austere beauty in the low light, and the Christmas markets in Bacharach and Boppard are genuine rather than commercial.