This time of year the sun's strong enough to heat things up very quickly in certain building types - or at least it is here in southern England, anyway.

For example, I live in a house with a flat roof. Yesterday coming home from work it was just over 28C in the west-facing bedrooms - and even with the windows open it took hours to cool to even 23C. It was 21C outside when I opened the windows.

If you're in a hotel with a flat roof and no a/c, I could easily imagine it becoming unpleasantly warm, especially if you're in a west-facing room.

Hopefully the OP will at least get the night comped in the end...