We loved our Black Sea trip a few years back.
Athens will be very hot, not particularly humid, Istanbul will likely be very hot and humid. We were there in June and it was then. Both in Greece before the cruise and Istanbul after, we had time to relax and pace ourselves--have a nap or relax in the late afternoon before dinner and the cooler evenings. Get out of Athens to an island or somewhere near the water if you can.
Wendy
------
Booked: Uniworld Egypt, 2015
Tauck Amsterdam to Budapest, 2016
Paul Gauguin, Societies & Tuamotus 2016
| 
