Cesky Krumlov

Actual, day-by-day, historical weather statistics are available for about the last ten years on the website timeanddate.com. The data is available for most places a tourist might want to go. I see lots of days over 80F. I'd want a/c. However, one night of being uncomfortably hot in a hotel wouldn't be the end of the world for me (as opposed to a multi-night stay in a larger town/city). Therefore, at some price differential I'd probably opt for the cheaper hotel without a/c; maybe I'd even get lucky with the weather. I'm not saying that's what you should do. How much does heat bother you? Are you traveling with someone else who's going to complain a lot about being uncomfortable in the hotel room?

CK July 2021: https://www.timeanddate.com/weather/@3077889/historic?month=7&year=2021

CK July 2020: https://www.timeanddate.com/weather/@3077889/historic?month=7&year=2020

CK July 2019: https://www.timeanddate.com/weather/@3077889/historic?month=7&year=2019

CK July 2018: https://www.timeanddate.com/weather/@3077889/historic?month=7&year=2018

CK July 2017: https://www.timeanddate.com/weather/@3077889/historic?month=7&year=2017

yes most buidlings are historical and old and lack AC. ask for a middle or ground floor rooms - they will stay cooler in case it gets hot

Excellent point. Avoid the top floor in the summer if you aren't going to have a/c!

You might try Hotel Villa Beatika. I believe they have A/C. Our stay there was very pleasant. https://villa-beatika.hotel.cz/services/