Yikes! If you are travelling to Bilbao between mid to late June 2020 be prepared for major sticker shock with accommodations! Bilbao is a host city for the upcoming Euros and hotel prices are through the roof - one place I checked that lists 85 Euros per night in May is showing over 600 Euros per night in June! Game days in Bilbao are June 15/20/24/28. If you find something reasonable during this period book it now and be prepared for crowds....
Or flip your itinerary to visit at less expensive nights. We have had to do that several times when planning a trip. Sporting events and Fashion Weeks escalate prices.
Right; flip your itinerary. We did that with Paris and Amsterdam when a big trade show in Amsterdam - I believe it was IBC - pushed hotel prices through the roof, and made finding available, suitable rooms in the city center AT ALL nearly impossible. I guess attendees for this annual Sept. show book rooms a year or more in advance, and many hotels set a large % of their rooms aside for the RAI attendee/exhibitor booking service. Anyway, to get around it we flipped our weeks: Paris first and then Amsterdam instead of the other way around.
So it’s like Madrid was the end of September when a normally €90 room was going for €300 due to a world medical congress.
Within the last year or so someone here ran into a similar problem in Madrid, I think--a city with a much larger supply of hotel rooms. In that case I think it was a play-off game, so the schedule probably wasn't set very far in advance.
Also beware bike races in France (it doesn't have to be the Tour de France to have a significant impact), classic-car rallies, and the like. That sort of thing can throw a monkey wrench into the itinerary of those of us who like to plan on the road and typically don't look at availability and rates until a few days before we plan to arrive.