Several hundred thousand people from the US have recent experience working in 120-140F weather wearing 50-100 pounds of equipment and heavy clothing, often doing labor a bit more strenuous than pulling drives or racking servers.
I'm not.
Relatively extreme temps are an issue, but can be overcome. If it requires a couple weeks of practice for your staff to get used to working in 100-120f low rh environments but saves huge amounts of energy, it is worth considering.
In a cloud hosting environment, you could eventually have non safe temperatures in active operation, lots of redundancy, and just do all your human maintenance during reduced power/temp windows all at once. Sort of like treating the data center as the inside of a computer. Either run multiple facilities or partition by thermal suite or hae the equipment power management be able to throttle cores for reducing heat.