Aug 4, 2019 - 8:30 AM
In general, at the end of September: no, you don't need air conditioning. Even with global warming, this summer was quite exceptional so far. June and July were the second warmest months since 1894 when measurements started. Only 2003 was warmer. Apart from that, late September is not as warm as July and August, and sunset will be earlier which helps too. Of course in the end it depends on what you're comfortable with, the weather at that time (can be anything from chilly to warm), the location (and altitude), the building and the room.
Last modified on Aug 4, 2019 - 8:36 AM by Arno