Nice anecdote, and of course there are always going to be some unknowns, especially when trying to make predictions about specific locations (and, as Yogi Bera would say, about the future
).
In this case, you do have some pretty basic physics to fall back on.
A warmer world will hold more water vapor in its atmosphere (an increase of about 7% water vapor for every degree C increase, iirc). That water vapor will come down somewhere, more often suddenly and in large quantities in most places. The far interior of continents generally will have less of this affect as they are far from the sea and will likely dry out generally, since the extra heat also can do a nice job of drying things out.
But of course the topography of individual locations will have the largest effect, along with how loss of Arctic sea ice affects weather patterns throughout the Northern Hemisphere (and beyond).
Because there are some unknowns, as there always will be, does not mean that we know nothing at all.
ETA: Physics dictates (and this is already happening) that a warming world will see the Hadley cell expand, and as it does, the dryness zone now associated with the Sahara Desert will move first into southern Europe (probably already part of what is happening in a drying Spain, Italy and Greece, last I looked), and then into central Europe. Probably the exact timing of these competing tendencies affecting specific areas accounts for some of the disagreement in models.