There may be no way to know, but I’ll ask anyway: How much rain would it take to get the Danube back to a level for cruising? I’m drawing some hope from the 14-day weather forecast.
Thanks so much for this great information. I'll be on the Romantic Danube with Viking (Budapest to Regensburg) in mid September. What's the minimum water level required for a Viking longship to make the entire route?