If you want to see Venice while keeping your feet dry, don't go when the sun has lots of spots. Peaks in solar activity cause the city to flood more often, apparently by changing the paths of storms over Europe.
Several times a year, but most commonly between October and December, Venice is hit by an exceptional tide called the acqua alta.
David Barriopedro at the University of Lisbon, Portugal, and colleagues were intrigued by studies showing the tides followed an 11-year cycle, just like the sun, showing peaks when the sunspots were most abundant.
They looked at hourly observations of sea level between 1948 and 2008, which confirmed that the number of extreme tides followed peaks in the solar cycle (Journal of Geophysical Research Atmospheres, DOI: 10.1029/2009JD013114).