Which months would you not go without AC in your Budapest lodging?

Probably not, if you had a fan. Depends on your tolerance. I leave mine off till June. Open the windows and turn on a fan.

Thanks, my tolerance is pretty high. Worst case, I can open windows at night to cool things down and close the curtains in the day to keep the heat out.

Be aware of the street scene outside of your hotel. You may want AC because there is a popular bar on the street under your window. Unless, of course, you are the one staying up until 3 AM.

jkh, good point ... excellent point. Especially if you are staying in District VII where the bars are very prevalent and stay open later. And there doesn't have to be a bar under your window. The streets are sort of narrow and there are four story buildings on each side so any noise in the street can bounce around a bit. Courtyard facing accommodations are always a big plus if you are a light sleeper.