Modern tech also makes it possible to turn arid environments into forests. I would start there. When you do that water starts to collect/accumulate and the area gets cooler.
On 99° days of unbearable heat and sun I can stroll under trees and be nice and cool in the 70°s. I do it all the time.
"Auroville has successfully reforested 5,000 acres of land and turned barrenness into a lush forest that acts as a massive pair of lungs for the region — so much so that the temperature within Auroville is measurably 3 degrees lower than in surrounding villages."
On 99° days of unbearable heat and sun I can stroll under trees and be nice and cool in the 70°s. I do it all the time.